System process hogging CPU, need help

[Marquis]

I've got this very annoying phenomena occuring on my Windows XP PC lately. I can't trace it back to any hardware or software installs that I've done or any specific tasks the CPU is performing that may account for this. What happens is, for no apparent reason, the System process (not the System Idle Process), all of a sudden starts using about 34% of the CPU, leaving the other 66% to the idle process. Once this happens, it basically stays at this level until reboot and meanwhile all my applications are affected. Mouse movements are jerky, Poker clients pause for long periods of time, any sounds that try to play will stutter, etc. Once I reboot, all is well and sometimes the PC will run for hours without it happening again. It always seems that after the first coldstart it will be guaranteed to happen within a half hour, and after a restart it won't happen again.

To try to fix the problem, I've run all sorts of anti-spyware and anti-virus software, run a defrag, removed some RAM that was recently added, removed a suspect hard drive, disabled many startup apps from running using msconfig, all to no avail.

If I knew what that System process even did, it might point me in the right direction, but scouring the web for information hasn't turned up anything. I'm pretty stuck and I really don't know what to try next. Any help will be greatly appreciated.

[PLOlover]

You might try things like disable searching for network drives and stuff like that. Tools->folders options->View in Explorer, the file viewer thingy not internet explorer.

[CrazyN8]

maybe turn off indexing. eh?

Post up your system specs, might make it easier to troubleshoot.

Run a virus scan, thats up to date? If not done yet.
What spy-ware software are you using? Is it up to date?

Try running memtest to see if you have any memory leaks.