CDRW Drive Not reading disc

I was backing up vital files to three cdrw discs using my Yamaha CRW2100E. I verified the written data using same drive AND my Pioneer DVD drive. I proceeded to reconfigure my HD for multiple OS’ and attempted to transfer the data off the discs. The first disc is problem free. The second would barely read enough to copy data. The last disc, the one containing the most valuable data, asks if I wish to install the UDF reader when in either drive. I can physically see that the data has been written on each disc, but cannot get third disc to read properly. Drivers and software are all identical throughout the process.