Hi John,
The "cyclic redundancy check" error usually means there's a problem with either the optical (CD/DVD) drive or the hard drive.
Do you have problems reading any other CDs or DVDs? If not, I suggest you have a look at the DVD first and see if it needs a clean. If all CDs read OK, but there's trouble with DVDs, it could be the drive itself which is "on the way out"!