iMac not reading CD correctly

Hello,
I am using Toast 5.0.2 to burn data cds. The cds are burned on another computer (9600) When I place the cd in my iMac, (model: M7443LLA; tangerine) w/ OS 9.2.2, I get a message box saying the the disc needs to be initialized because it is formatted for PCs. Perhaps I need to upgrade Toast. The strange thing is, it will load properly on a G4 and the 9600. We have two identical iMacs here and the problem is the same on both. Any suggestions?
Thanks,
Tyson