Hi Frondar,
Thanks for letting us know how it went, I'm glad you managed to get everything sorted.
As for the cause, it's really hard to say, but I would hazard a guess at corruption in a core Windows Update file, or a dodgy hard disk. There isn't many signs of the latter being the cause here, but it has to be something fairly substantial for it to cause 20,000+ problems. It might be worth trying a chkdsk, just to make sure everything is in order:
Disk Check
Tom