System 13% cpu usage - constant-

[Graham]

Pc intel 4 core , win-xp-pro , all patched to date .

Normally , the pc , with no applications open, when checking the
cpu usage , sits round 0 % , with memory for the 'system' 244 K,
none of the 4 cores showing any usage or history (apart from the
odd flicker)

Lately , after the pc has been on for half a day or so, and in the
evening, it develops , a odd problem, in that applications tend to
hang and judder , and the system cpu load shows a constant 13% ,
1 of the 4 cores showing 100% usage , same memory usage .
closing all app's , still leaves this 13% constant load ..

malwaerbytes, trend house micro , avast , spybot all show nothing ,
the windows on-line tune/up reports a trojan , but dose not offer
to remove it ..

nothing extra shows in the applications or process

The pc runs fine until this system-13% cpu usage starts .. but
what is causing it ?

G..

 

[Jo-Anne]

I ran into this problem recently, as did a lot of other people. In my case
and many others', it turned out to be a problem with Automatic Updates. I
had posted to the microsoft.public.security newsgroup, thinking it was
malware.

MowGreen responded on August 18: "There is *definitely* a Hard Drive I/O
Read bytes issue with XP systems that have been opted into Microsoft
Update(MU). Temporarily opting the system out of MU is the *only* way to
resolve it for now. It's not a CPU cycle issue, it's stemming from I/O Read
bytes to the Hard Drive."

I had Automatic Updates set to just inform me of updates, not to download
them--but that wasn't enough. The only way to stop the CPU usage was to opt
out completely. I subscribe to the Microsoft Security Response Center
through Google Reader:

http://blogs.technet.com/b/msrc/

so I'll know when to check the Microsoft Update webpage for updates--at
least until this issue is resolved. It seems to have the worst effect on
older computers with not much RAM.

Jo-Anne