Nero 7 hangs when trying to convert audio CDs to audio files

I have a strange problem with Nero 7. It hangs when trying to convert certain audio CDs to audio files. The screen where it hangs is the "accessing disc please wait" screen.

The strange thing is, some CDs get passed this screen fine and the list of tracks show up, ready to be converted, while others just hang. For these "hanging" CDs, when I press the Eject button on my ASUS DRW 1814BLT drive, the list of tracks appeared for a second before disappearing again due to the drive being opened.

Does anyone know what the problem is and how to fix it?

Thanks...