[mltb]

I have a PowerMac G5. I can successfully burn, verify, and mount a DVD with Toast 6.1.1. Then, after I have ejected the DVD, I load it back again; but this time, it doesn't get mounted and ejects. I load the same DVD onto my PowerBook G4, and it reads just fine.

The DVDs I am using are TDK DVD-R. I have never had a problem with this brand in the past, until I bought a new pack.

What might be the problem?

[tsantee]

The most likely problem is between the drive and the OS. OS X will automatically instruct a drive to eject a disc if it is not recognized. You might try a laser cleaning disc to see if that is why the drive isn't reading the disc. It could be the drive is failing. Maybe it is one of those quirky OS issues that appear after doing an incremental System Update - those are fixed by downloading an applying the Combined System Update. If it was a media issue I'd expect the disc to fail while being burned.