One big unknown in your system is Service Pack 2 RC 1.
Microsoft do not recommend using this in any 'production' systems - it's released for evaluation only. Things will change from RC1 (RC stands for Release Candidate) - the release itself is probably some months away. RCs and public betas are probably more stable than private betas, but they are still beta grade, unsupported code. Of particular note is that there's not necessarily any fixes forthcoming for security problems found that affect beta service packs, though the fixes will almost certainly be rolled into the final service pack.
Whilst there are a lot of fixes, there's also bugs. It's also supposedly not the cleanest thing to uninstall (WinXPnews promise more information on this in the next issue).
If possible, try to return to Service Pack 1 plus all the hotfixes from Windows Update.
(who notes that whilst he's been writing this, wesociety has written a very similar response)