DVD Drive saying 'Wrong medium type'

Hello, over the last week, I have had trouble mounting data CDs. Usually, when using YaST, it mounts the first CD, then when it asks for another CD to be inserted, it fails and the drive will not mount another CD until reboot. If I reboot, the drive is fine for a while, then it fails again. I have not done anything to the drive that I can think of. I have started using Gnome, but still use the same applications as I have always done. any ideas what might be wrong and how I can fix it? thank you joss -- http://www.josswinn.org