Thanks for posting back.

Now you have me wondering what format those Windows files are in or how the disk was written? I've several CDs and DVDs that are split with Windows and Mac programs. However, I can read both sides of the disks from my Mac.

The only thing I can think of is if the Windows files on that disk are in an executable format and have to be read from Windows. I've run into that before but the disks were Windows only.