explorer.exe _apparently_ using 100% CPU?

[J. P. Gilliver (John)]

As of somewhere in the last few days, explorer.exe _seems_ (in task
manager) to be using 100%, most of the time, of my CPU. But the machine
isn't sluggish: YouTube is no more jerky than usual, a locally-played
video plays as smoothly as ever ...

I've scanned; I've checked my HD's SMART; my wifi MoDem isn't showing
excessive activity, so I've not been recruited into a botnet; in fact,
if it wasn't for task manager _saying_ the CPU was at 100% most of the
time, I'd not know anything was amiss - except that an explorer window I
have open seems to jump to have the focus on My Documents, occasionally.

Any ideas?

I've only been looking at Task Manager to keep an eye on what Firefox is
up to, as that _was_ getting sluggish after being used for a bit.
(Oddly, even that - Firefox - doesn't seem to be unusuable.)

 

[BillW50]

As of somewhere in the last few days, explorer.exe _seems_ (in task
manager) to be using 100%, most of the time, of my CPU. But the machine
isn't sluggish: YouTube is no more jerky than usual, a locally-played
video plays as smoothly as ever ...

I've scanned; I've checked my HD's SMART; my wifi MoDem isn't showing
excessive activity, so I've not been recruited into a botnet; in fact,
if it wasn't for task manager _saying_ the CPU was at 100% most of the
time, I'd not know anything was amiss - except that an explorer window I
have open seems to jump to have the focus on My Documents, occasionally.

Any ideas?

I've only been looking at Task Manager to keep an eye on what Firefox is
up to, as that _was_ getting sluggish after being used for a bit.
(Oddly, even that - Firefox - doesn't seem to be unusuable.)

Explorer.exe does a lot of things. As a shell which you are probably
using controls the whole desktop. Explorer as a file manager just does
that. But Explorer also links to IE and other file tasks as well. So I
would ask if there are other things opened? Like the Explorer in file
manager mode or IE?

 

[Paul]

As of somewhere in the last few days, explorer.exe _seems_ (in task
manager) to be using 100%, most of the time, of my CPU. But the machine
isn't sluggish: YouTube is no more jerky than usual, a locally-played
video plays as smoothly as ever ...

I've scanned; I've checked my HD's SMART; my wifi MoDem isn't showing
excessive activity, so I've not been recruited into a botnet; in fact,
if it wasn't for task manager _saying_ the CPU was at 100% most of the
time, I'd not know anything was amiss - except that an explorer window I
have open seems to jump to have the focus on My Documents, occasionally.

Any ideas?

I've only been looking at Task Manager to keep an eye on what Firefox is
up to, as that _was_ getting sluggish after being used for a bit.
(Oddly, even that - Firefox - doesn't seem to be unusuable.)

When I look in my Task Manager

Explorer.EXE PID=380 Priority = Normal <--- (File) Explorer
iexplorer.exe PID=332 Priority = Normal <--- Internet Explorer

If the file explorer is railed at 100%, that should have
an effect on your system. Especially if it is a single core.
If it's multi-core, then one core is railed, and the other
cores remain idle.

Normal Priority, means it will fight for cycles with
other Normal Priority tasks. Which is most of them.
If the thing is assigned a below normal priority, then
other things get to execute ahead of it in a sense. And
there is less system impact. You can do properties in
Task Manager, and see what the priority is set to.

While the PID number is not absolute in any sense,
it would be normal for those to have started early
after the system booted. PID numbers roll over and
get re-used, so for a system with a long uptime, you
can't say anything definitive about say Firefox PID.
But if you've "never lost the desktop", then chances
are the same Explorer is still running as was there
when the system booted.

*******

Maybe it could be computing thumbnails for movies ?
Do you have a movie folder in which thumbnails
are being generated ? I think I did that as an
experiment once, and I think even when the movie
folder was closed, the damn thing was just cranking
away.

I expect you'll find more than a few hits for
these symptoms in Google (100% Explorer CPU).
It's a common problem, with malware as a root
cause in some cases.

You could also use Process Monitor, and see what
general activities are going on. Lots of Registry
accesses ? That's normal. Lots of file accesses ?
That may not be normal, depending on whether there
is an AV at work, the indexer is running, and so on.

(Process Monitor 3.05)

http://technet.microsoft.com/en-us/sysinternals/bb896645

I just traced on that process name (Explorer.EXE) and
it was pretty quiet at the beginning of my trace. But
as soon as I made some adjustment on my system, the Procmon
log started to fill up. Have a look and see what's up.

HTH,
Paul

 

[J. P. Gilliver (John)]

Explorer.exe does a lot of things. As a shell which you are probably
using controls the whole desktop. Explorer as a file manager just does
that. But Explorer also links to IE and other file tasks as well. So I
would ask if there are other things opened? Like the Explorer in file
manager mode or IE?

It's only happened in the last few days, and is now the case from
startup: I used to get low (8, 17, that sort of percentage) CPU usage at
"idle", i. e. after all had settled down. And I hardly ever use IE -
Firefox is my browser of choice (recent versions of which _have_ tended
to suddenly start eating CPU, but that's not running at this moment).

 

[jim]

As of somewhere in the last few days, explorer.exe _seems_ (in task
manager) to be using 100%, most of the time, of my CPU. But the machine
isn't sluggish: YouTube is no more jerky than usual, a locally-played
video plays as smoothly as ever ...

I've scanned; I've checked my HD's SMART; my wifi MoDem isn't showing
excessive activity, so I've not been recruited into a botnet; in fact, if
it wasn't for task manager _saying_ the CPU was at 100% most of the time,
I'd not know anything was amiss - except that an explorer window I have
open seems to jump to have the focus on My Documents, occasionally.

Any ideas?

I've only been looking at Task Manager to keep an eye on what Firefox is
up to, as that _was_ getting sluggish after being used for a bit. (Oddly,
even that - Firefox - doesn't seem to be unusuable.)

100% idle ?

 

[J. P. Gilliver (John)]

In message

100% idle ?

No, the System Idle Process (which normally gets 50-80% of the CPU) is
right at the bottom now.

 

[J. P. Gilliver (John)]

As of somewhere in the last few days, explorer.exe _seems_ (in task
manager) to be using 100%, most of the time, of my CPU. But the
machine isn't sluggish: YouTube is no more jerky than usual, a
locally-played video plays as smoothly as ever ...
I've scanned; I've checked my HD's SMART; my wifi MoDem isn't
showing excessive activity, so I've not been recruited into a botnet;
in fact, if it wasn't for task manager _saying_ the CPU was at 100%
most of the time, I'd not know anything was amiss - except that an
explorer window I have open seems to jump to have the focus on My
Documents, occasionally.
Any ideas?
I've only been looking at Task Manager to keep an eye on what
Firefox is up to, as that _was_ getting sluggish after being used for
a bit. (Oddly, even that - Firefox - doesn't seem to be unusuable.)

When I look in my Task Manager

Explorer.EXE PID=380 Priority = Normal <--- (File) Explorer
iexplorer.exe PID=332 Priority = Normal <--- Internet Explorer[/QUOTE]

When I look in my Task Manager, I don't see any PIDs or priority column;
I have XP Home, does that make a difference? (I don't usually have IE
running.)

If the file explorer is railed at 100%, that should have
an effect on your system. Especially if it is a single core.
If it's multi-core, then one core is railed, and the other
cores remain idle.

It is having _some_ effect, but not making everything sluggish, which is
what I'd have expected.

Normal Priority, means it will fight for cycles with
other Normal Priority tasks. Which is most of them.
If the thing is assigned a below normal priority, then
other things get to execute ahead of it in a sense. And
there is less system impact. You can do properties in
Task Manager, and see what the priority is set to.

While the PID number is not absolute in any sense,
it would be normal for those to have started early
after the system booted. PID numbers roll over and
get re-used, so for a system with a long uptime, you
can't say anything definitive about say Firefox PID.
But if you've "never lost the desktop", then chances

Not so far.

are the same Explorer is still running as was there
when the system booted.

*******

Maybe it could be computing thumbnails for movies ?
Do you have a movie folder in which thumbnails
are being generated ? I think I did that as an
experiment once, and I think even when the movie
folder was closed, the damn thing was just cranking
away.

Well, I don't have significantly more movies than before the behaviour
started. (My default movie icon is the VLC cone, not a thumbnail icon,
anyway.)

I expect you'll find more than a few hits for
these symptoms in Google (100% Explorer CPU).
It's a common problem, with malware as a root
cause in some cases.

I still have a lot of looking to do!

You could also use Process Monitor, and see what
general activities are going on. Lots of Registry
accesses ? That's normal. Lots of file accesses ?
That may not be normal, depending on whether there
is an AV at work, the indexer is running, and so on.

(Process Monitor 3.05)

http://technet.microsoft.com/en-us/sysinternals/bb896645

I just traced on that process name (Explorer.EXE) and
it was pretty quiet at the beginning of my trace. But
as soon as I made some adjustment on my system, the Procmon
log started to fill up. Have a look and see what's up.

HTH,
Paul

I will in time (though I've looked at such logs before and not really
understood them!).

 

[Paul]

When I look in my Task Manager, I don't see any PIDs or priority column;
I have XP Home, does that make a difference? (I don't usually have IE
running.)

Try View : Select Columns.

I have PID, I/O Read Bytes, I/O Write Bytes selected
on mine. The last two, allow me to figure out when a
backup is about to finish.

Paul

 

[J. P. Gilliver (John)]

When I look in my Task Manager, I don't see any PIDs or priority
column; I have XP Home, does that make a difference? (I don't usually
have IE running.)

Try View : Select Columns.

I have PID, I/O Read Bytes, I/O Write Bytes selected
on mine. The last two, allow me to figure out when a
backup is about to finish.

Paul[/QUOTE]
Thanks.

I now have Firefox open - which tends to be a CPU hog of late (why I was
looking at Task Manager in the first place). Total CPU is still more or
less 100% all the time, but now it's mostly Firefox, with Explorer
"taking up any slack" as it were: in other words, Explorer, though using
a lot of CPU if it can, isn't high _priority_. If I close Firefox, I
think Explorer will shoot back to near 100% again.

I am just more than a little curious what it's _doing_! I googled as you
suggested, and by far the commonest suggestion seems to be that it's
scanning big .avi files to make icons out of them. But I don't think it
can be that: (a) my icon for most movie files is the VLC cone rather
than an icon, (b) I've made the registry amendment most of them mention,
(c) it's been going on for _days_ now, (d) it happens from bootup before
I have any folders open. (And (e) I haven't downloaded any _huge_ movie
files lately anyway.)

Ho hum, I'll keep reading the google suggestions! It's not a _major_
problem: the main one is the side-effect that it changes focus (to "My
Documents") occasionally, which is a bit of a pain as my news/email
client (Turnpike) operates as a shell extension (so loses its place).
Only at fairly long intervals though.

 

[Paul]

Thanks.

I now have Firefox open - which tends to be a CPU hog of late (why I was
looking at Task Manager in the first place). Total CPU is still more or
less 100% all the time, but now it's mostly Firefox, with Explorer
"taking up any slack" as it were: in other words, Explorer, though using
a lot of CPU if it can, isn't high _priority_. If I close Firefox, I
think Explorer will shoot back to near 100% again.

I am just more than a little curious what it's _doing_! I googled as you
suggested, and by far the commonest suggestion seems to be that it's
scanning big .avi files to make icons out of them. But I don't think it
can be that: (a) my icon for most movie files is the VLC cone rather
than an icon, (b) I've made the registry amendment most of them mention,
(c) it's been going on for _days_ now, (d) it happens from bootup before
I have any folders open. (And (e) I haven't downloaded any _huge_ movie
files lately anyway.)

Ho hum, I'll keep reading the google suggestions! It's not a _major_
problem: the main one is the side-effect that it changes focus (to "My
Documents") occasionally, which is a bit of a pain as my news/email
client (Turnpike) operates as a shell extension (so loses its place).
Only at fairly long intervals though.

That's where Process Monitor program comes in. You can
have it capture a minute of activity, and look at all the Firefox
or Explorer file read or write activity. If Explorer is making
thumbnails, you should see a sustained stream of reads to
a file ending in .avi or whatever.

If you thought it was malware, then Process Monitor would be
a waste of time. But if you thought it was a functional failure,
it might require the collection of some tell-tale data,
to figure out what is broken.

Paul