Oh, the dreaded CRC error. I *always* have that problem when I install, even if I install from a download! (some are discs, some are downloads)
My discs are in perfect condition and my computer should be, too, so even my hubby couldn't figure out what causes it.
The only thing that works is to cancel and try again. And again. And again. Eventually, it will go trough, but it's very frustrating.
In my case, the file in question changes each time, and then suddenly it just installs fine.
I recently did a complete re-install with all EPs excpt Showtime and because of the errors, it took all day. I had downloaded the patches from online, and got CRC from installing them, too, so it's not just from reading a disc. :/