Liteon 1635s problem

The picture looks good, only it’s a regular CD-R inserted with 2 sessions on it, disc closed of course. I tried reinstalling CloneCD but it didn’t help. The drive is hooked up to a PCI ITE Ata Controller. Both my Benq 1640 and Teac w524e recognize the disc correctly. Everything used to be OK until a few days ago. Is my Liteon 1635s bust? Can the problem be software related?
The sessions were recorded using Nero 6.6.1.4. A test disc which I just created using Nero CD-DVD Speed is recognized correctly. What’s going on?