I'm really probably the worst source of help,
It was something you downloaded from Windows Update site? hmm.. Have you tried system restore, perhaps it would take you to a point prior to the download.
There are so many possible problems or conflicts that it would be hard (for me anyway) to say what it could be. It could be some capability issue with software or even hardware or perhaps some stupid little setting in windows somewhere.
I've been having a host of problems myself with Windows 7, I like it, but I may end up going back to XP lol.
Last night, due to the freezing window problem I was having, I tried installing a new invidia driver from their site. After reboot, my computer would load up, and then the screen would go black. I fought with that for hours, even reformatting and reinstalling windows (again) Finally by dumb luck, it was working again normally. Course, then I installed a game and went back to windows update and logged out.. so I'll probably get home tonight and have more issues.
If I have more issues tonight, im tossing windows 7 out the damn window!