One possible reason for a very slow boot up is that you may have
unknowingly disabled XP's built-in periodic "boot time optimization
defrag" from running. This will typically run once every couple of days,
if enabled and the system "goes idle" (meaning it's not doing anything and
the screen saver activates). The most common way it's turned off is by
disabling the Task Scheduler Service, and old W98 "tweak" that really
should not be done in XP.
One way to check is to look in \windows\prefetch and check the file
layout.ini; its date will be the date of the last run. It should be at
most few days old, no more.
you can force this layout.ini rebuild operation to take place w/ this
command:
%windir%\system32\rundll32.exe advapi32.dll,ProcessIdleTasks
after doing so layout.ini should have a new date (it does other things
too, WMI related etc, but that's another story). This operation normally
takes about 2 minutes (watch the HD light), but if it takes only 10
seconds or so then the layout.ini DID get remade, but the defrag operation
did not run (see below); you can then force it too, with this command:
\windows\system32\defrag C: -b
[or whatever your drive letter is]. the -b say to do only the fast
boot-time defrag. It should take about 1-2 minutes, no more. Normally it
will run on its own as part of the first command above, but it may be
disabled via this reg key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
CurrentVersion\OptimalLayout\EnableAutoLayout=0 ; default is 1
if it's set to 0 try to figure out why; it defaults to 1, but some third
party defragers do disable it when they are installed (because they can do
the job better). If that's the case then use the 3rd party tool after
doing the layout.ini rebuild.
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regarding what stratup tasks can/should be turned off, you just have to do
your research. there are lots of sites that can tell you what a
particular startup task is and whether you really need it; just use google
to search on its name and you'll find advice.
I recommend the Startup Control Panel:
http://www.mlin.net/StartupCPL.shtml
use it to disable those items that do not have there own option to "start
when windows starts". [always check if the item has its own means first,
and use that if possible.] Lots of these startup items are just "update
checkers", "tray tools", fax monitors, etc, and they can be safely
disabled. But use google to research it first on an item-by-item basis.
As far as Services, google for Black Viper (a long gone but often archived
site), and The Eldar Geek. Both have good advice re: Services that can be
disabled.
Good Luck.