can't run iTunes or QuickTime

Hello all, I've read several threads here & tried a lot of things, but to no avail...
After PC crash, I had to reinstall WinXP. Now trying to reinstall iTunes & QuickTime. Installers say they were installed successfully, but as soon as I try to run either, I get the "QuickTime Player has encountered a problem and needs to close." with Error Signature:
EventType : BEX P1 : QuickTimePlayer.exe P2 : 7.50.61.0
P3 : 4837c166 P4 : QuickTimePlayer.exe P5 : 7.50.61.0 P6 : 4837c166
P7 : 0000130d P8 : c0000409 P9 : 00000000

I get similar error when trying to run iTunes, so I imagine they're related.

If I try to uninstall QuickTime from Control Panel->Add/Remove Programs, the only QuickTime shown looks like the installer exe, not the actual program. Anyway, if I try to uninstall that, I get "Fatal Error during installation" and it quits. If I run the QuickTime installer & choose Remove, it goes through a few things & then I get "The installer encountered errors before the requested operations for QuickTime could be completed. To retry these operations at a later time, please run the installer again." Of course I tried later, but same thing.

Also tried uninstalling everything manually (removing QuickTime folder from ProrgramFiles, removing Quicktime files from System32, etc.) but didn't help. And I removed all QuickTime, iTunes, Bonjour, etc. using Windows Install CleanUp.

None of these seem to work... Any suggestions?
Thanks!