Has he been tweaking the data files? Every time I screw up there, I get an "unspecified error" crash... A typo is more than enough.

The unpacker, is a program allowing you to access the data files, as they are packed when you install the game - hence "unpacker". There are two files there you need to delete for the game to work.

Other than that, what is happening when the game crashes? Is he encountering a specific enemy, doing a specific thing?

Oh, and of course, MAKE SURE he has the latest video drivers.