Repairing a bad CD-RW Disk

[francoamerican5]

I got the Sony DRU-700A Dual DVD+-RW DL/CD Burner about a month ago and I have been experiencing difficulties with CD-RWs. I have had to replace one disk because I kept getting a bad CRC error. I was able to copy everything fine to a new cd.
My other CD-RW is a backup CD with about 4 years worth of downloaded programs for my computer. I never thought of backing up the backup. I used to use a LG CD burner & never had problems with drag to disk. (Roxio 7) But with my backup disk, I tried copying a file to the disk, it took way to long to eject... approx 1-2 mins. When re-inserting the disk in I now get a: E:\ Is not accessible. The Disk Structure is corrupted and unreadable.
I ran ScanDisk and it checked the disk & file integrity and told me everything was fine...

My Question is there another way to fix the disk without losing ALL my data? Is there something wrong with the burner? (After the disk messed up, I found a newer firmware for my drive, so maybe that was the problem... I havent tried screwing up another disk yet.) OR is it that I am using Roxio Media 7 instead of the bundled Nero software that came with my Sony?
I would Appreciate your comments & suggestions. Thanks!!

[texascbx]

Try CD/DVD Diagnostic.

[burninfool]

Use IsoBuster to extract the data and Nero to burn.

[francoamerican5]

I tried ISOBurner and it gave me back some files. There is a big part that came up as Non-Allocatable Space. Is that unrecoverable? I didnt want to dish out $60 to try CD/DVD Diagnostic. Is there a way to recover this space or am I gonna have to be happy with what I got...?

[Han]

Another great recovery tool is BadCopy Pro, but you can't expect miracles. I'd also try to read the 'bad' disc in a different, preferably better reader.