Patch it first and copy the music file to your directory.
Original shipping version of D2 had a poor implementation of copy protection on the CD that made it unreadable by some models of drives. It was insidious though, as it'd look like it installed properly, but sometimes files would be corrupted.
The other part of the problem was sometimes it'd install correctly, but read the music wrong and crash, corrupting the install.
Once you crash, you're screwed. Odds are the game files are corrupted.
Install the game, copy the music, apply the patches, and keep doing it until it's ok.
You'll never hear about this officially though, Blizzard went to great lengths not to mention what was actually happening, and only publicly acknowledged Plextor(I think) drives being unable to read the discs at all.
Trust me, I fought with this one for *weeks* when it first released until I figured out what was going on.