Timstuff said:
It will get pretty far, but then at the end it always effs up and gives me an error message.
All I can think of it is that something might have gone wrong during extraction. The same thing happened to me once, and I ended up having to re-download the archive. I realize having to download it again isn't the most appealing prospect, but I'd recommend doing so before you waste another disc.
That's all I can suggest. Sorry I can't be more help. :-(