That is part of the problems currently with the mixed "ide-scsi"/atapi stuff in the kernel.

Kinda why they are swapping in the device mapper...

Also, if it's a "generic CDROM" isn't as compliant with ATAPI as it should be ... well that just complicates the problem more.

I've had that problem with everything except... Kernels with the some of the I/O patches out there ones design to account for spin-locks and time-outs and such...

Which version of the Kernel you running? 2.4.18+ has much better handling... but will still bung-up like that in specific configs and situations.

Yes, I do keep to much in my head... a plethora of useless/useful information... just wish I could speak and write it all down sometimes... ;)