If you legally own the disc then you can just copy it for purpose of backup for situations such as this. Use nero, poweriso or some other cd buring software to create an image of the disc then reburn that image to a new cd. Let the image process run as slowly as it can so it doesn't cause read errors during copy.
Legal Stuff:
Copyright and Digital Files
http://www.copyright.gov/help/faq/faq-digital.html
Fair Use
http://www.copyright.gov/fls/fl102.html