xp pro sp3. The drives are recognized by the bios and by windows. The respective icons appear as they should. When I insert a disc, the icon changes to show that a disc is indeed in the drive. When I try to read from the disc, I get a blank screen, or a message telling me to insert a disc. After some experimenting I found that if I booted with a disk (not bootable) in one of the drives, that drive could read the inserted disc, except for a music disc. I could even change discs, but just for the current session, and just that drive. If I rebooted without a disc in a drive, neither drive could read an inserted disc. While this works with either drive, it does not work with both together. I can also burn discs. I don't know when this started, because sometimes weeks go by without my needing to use an optical drive. I have tried uninstalling both drives, and Windows reinstalls them properly on the next reboot. Incidentally, if a drive was reading discs, it would continue to do so after recovery from standby or hibernate. Any ideas?