Hmmm.... seems like you've got a good handle on things....
1) I suppose there's a chance of a virus... stealing CPU time..... but that
seems remote. Unless you've never run antivirus software, and do not keep
it updated..
2) I still suspect a software configuration issue... Have you read through
these recommendations?
http://www.microsoft.com/WindowsXP/expertzone/columns/mcfedries/03june16.asp
One recommendation is to spread your paging file over two physical drives,
if you have them.... and you do.
A tiny corruption, or mis-setting, can have deleterious effects on an
otherwise stable system.
3) Have you tried purging the paging file (by setting it to 0), rebooting
cleanly, then re-establishing the paging file?
Unless I can think of anything else, I am afraid you'll have to continue
your search, or wait for a reply from someone more knowledgeable than me.
4) One more general thing... due to subject overlapping, and common
confusion of News Group focus, make sure you search the
microsoft.public.windowsxp.perform_maintain, and the .help_and_support
groups - not just this hardware one. I usually do a search on the newsgroup
folder (then ctrl+shift+f) for specific phrases, and it scans all the
microsoft.public groups that I've added... Also, use Google advanced
searches....
http://www.google.ca/advanced_search?hl=en Very helpful in
looking up solutions to the myriad messes we find ourselves in, from time to
time.
Regardless, please post back with your inevitable solution (I have faith
you'll find it)
Good luck,
-Lawrence in Seattle