After Vista has been running in normal mode for 2-3 minutes (regardless of whether I log in) it freezes up and all I can do is move the mouse around. This doesn't occur in safe mode or running Ubuntu. I have a T400 so I've tried both graphics cards and that hasn't made a difference. I have a hunch the problem is related to Explorer in normal mode, but I could be entirely off base.
Also, when using system restore in safe mode, it BSODs after starting the process.
The only Windows Update I made that day was a Defender definition update. The actual problem started when I was running WinDirStat. About 2/3 through my OS froze up, so without thinking I just yanked the battery out and put it back in, and that's when things went downhill. I've since uninstalled it, but that didn't do anything (not that I expected it to). It might be related but it could have just been a coincidence.
I'm open to pretty much any ideas for troubleshooting, or I can post more information if anything would help. At worst, I do have a free Windows 7 upgrade I could try, but I'd rather that be a last resort.