from what you are saying its probably the CD-RW disc. of course, in the relatively unlikely and sad event that is is your hard drive, there are still ways to recover the daya. one of the easiest ways that most people are afraid to do is to put the drive in the freezer for a few hours, or overnight (yes, i'm serious). anyway, boot the drive and retry. ive done this countless times with great results and no drives killed from the process. anyway, it shouldnt get to that.
--Poly