Sadly, I've run into the same problem. It seemed rather sudden to me, because it was working for a while after I put in my new DVD burner. However, I think it may have had something to do with installing Impression, which claims to be able to burn DVD's as well, but isn't very good at it. It may have changed something that I wish it hadn't, and now EAC won't read audio CDs.

Have you installed any programs remotely related to the CDROM drives lately?