CRC errors are a problem with the cd itself yes....
Its possible that the files that became corrupt are those of the other characters.
You can try to create an image of the game on your har disk and install it from there, or you can borrow a friend's copy....
If another CD doesnt help, then there may be something wrong with your cd-rom.... but check the cd first...
If you can, use a cd cleaner... if you dont have a cd cleaner, you can do a fairly similar job with a spray can deoderant (NOT ANTI-PERSPIRANT), and a very soft cloth (like the type the use with reading glasses / spectacles) Wipe from the INSIDE to the OUTSIDE, not in circles....
Hope this helps...