It's somehow worse than I imagined. A fresh install of windows (formatted the hard drive and everything!)

...the problem still persists.

I did two things after installing xp pro... I updated it fully (sp2 + all later high priority updates), and I installed/fully updated Norton Antivirus 2005.  I uninstalled Norton, thinking maybe some update to it fudged things up.

...the problem still persisted.

The only other explanation that makes sense is that some update to windows screwed something up. Or maybe there is some worm/virus/whatever that can very quickly attack a fresh install before it can be fully updated.  One that can get through my router's protection too.

If anyone can find information about this, let me know.  HP PrecisionScan hangs at its splash screen (the only "fix" for this I could find didn't work), Paint Shop Pro 9 hangs (after reboot... it works until I reboot) when it goes to initialise JascCmdFile.dll, and CuteFtpPro (I assume it will not work, though I haven't installed it) fails whenever it tries to create an FTP session.