This happened to me, back in the days of Windows 7 RC. Chances are, you didn't do a FULL format on the drive Windows 7 is installed on.
Quick Format - Deletes all data and creates file system structures
Full Format - Checks for bad sectors, repairs them, deletes all data, and creates file system structures
After this happened to me, about 8 hours later in fact, every time I tried to download a file or save something to my drive, it would say something along the lines of "The file system is corrupt". I suggest doing a FULL format on your Windows 7 drive, and doing a clean install. Be sure to backup all data before hand. Hope this helped a bit.