Good news

I put in a CD drive that hadn't been broken, and it works fine. So I guess that adds evidence to support fingal's theory on it being a firmware problem with the original drive.

However, since I can keep both drives in the computer at the same time, and just use this second drive when I want to access audio CDs, I'm wondering whether it might be safer not to try changing the firmware... We can more or less consider the problem solved, anyhow.

Thanks for all your help guys
Giles