You know, a re-install... :P
The game does get it's graphics files corrupted fairly often, I had my character select screen destroyed once. I've heard that Win file systems can do some nasty stuff if you don't leave about 5% free space on the drive, and I was getting my D2 corrupted quite often when the drive was full. Supposedly, setting all the .mpqs but "patch_d2.mpq" to "read only" should reduce the chance of corruption, it didn't help me in my specific full-hard-drive case, but people have reported that crashing for other reasons can introduce corruption into these data files if they aren't read only.
The game does get it's graphics files corrupted fairly often, I had my character select screen destroyed once. I've heard that Win file systems can do some nasty stuff if you don't leave about 5% free space on the drive, and I was getting my D2 corrupted quite often when the drive was full. Supposedly, setting all the .mpqs but "patch_d2.mpq" to "read only" should reduce the chance of corruption, it didn't help me in my specific full-hard-drive case, but people have reported that crashing for other reasons can introduce corruption into these data files if they aren't read only.