Well, hopefully a reformat will fix you up Lynch. This has been a mystery indeed.

If the repair failed to fix the problem, then I'd say it was something beyond just an OS problem.. another program more than likely was causing the issue.. or it was hardware related like an actually memory or hard drive issue.

I was going to mention to run a chkdsk /f command.. to check the disk and fix any problems..

But with a reformat that should do it for you. Let us know how it turns out.