CD/DVD Diagnostic Integrity Checker?

You cannot repair a CD or DVD even if it were damaged. If there be any software to check an optical disc you would find it at VersionTracker or MacUpdate.

The best check is to mount the disc, open a Finder window to check that the files you wrote to it are present and accessible.

I would suggest you buy Roxio Toast:

http://www.roxio.com/

and use that to burn CD/DVD media. Toast allows you to select the burn rate (the lower the better) and also verifies the integrity of the disk after burning so that you know that disk is an exact copy of the files/folders you burned, and also works!

Also, be selective in your choice of media: most of here prefer Verbatim or Fuji CD-R and DVD-R, and Maxell also has its adherents.

The foregoing applies to both audio, video and data.

Disk Utility and Finder can verify the disc after burning (and let you choose the burn speed). Be sure to use a good brand disc, such as Verbatim.

Finder always does a verify, but you can abort it with the ⓧ at the end of the progress bar.