Up until a short while ago, data DVDs were automatically mounted when I inserted them in my DVD drive. But now, for some reason, this no longer happens.

Just now, for example, I burned several divx files to a DVD using K3b. I reinsert the disk. K3b appears to recognize it a DVD of its own creation, but Nautilus doesn't mount it; I don't see the DVD drive icon browsing computer:/// in Nautilus, nor do I even see /dev/hdb using fdisk.

Here is what I see in dmesg:
ISO 9660 Extensions: RRIP_1991A
cdrom: This disc doesn't have any tracks I recognize!
hdb: DMA timeout retry
hdb: timeout waiting for DMA
hdb: status timeout: status=0xd0 { Busy }
ide: failed opcode was: unknown
hdb: drive not ready for command
hdb: status timeout: status=0xd0 { Busy }
Since installing FC3 several years ago, I have had the "mount removable media when inserted" option selected on the Storage tab of Removable Drives and Devices under Preferences.

Has anyone idea what is going on? I am at a loss.

I'm runing FC6 with kernel 2.6.19-1.2895.