I have 2 dvd drives on my system, both were working fine with Slackware 11 and I've been running 2.6 kernels for the last couple of years too. After upgrading to Slackware 12, my dvd drive, hdc, stopped working. The hdd dvd drive works fine. I can burn with it too.

I can issue these commands and both work fine:
eject /dev/hdc
eject /dev/hdd

Whenever I pop in a movie or a data dvd/cd in hdc the system locks hard. Nothing responds, not networking, not the keyboard, NOTHING. I have to hit the reset button. I can boot recue media from this drive with no problem.

Here are some selected cuts from dmesg:
hdc: _NEC DV-5700A, ATAPI CD/DVD-ROM drive
hdd: LITE-ON DVDRW SHW-1635S, ATAPI CD/DVD-ROM drive
hdc: ATAPI 40X DVD-ROM drive, 256kB Cache, UDMA(33)
Uniform CD-ROM driver Revision: 3.20
hdd: ATAPI 48X DVD-ROM DVD-R CD-R/RW drive, 2048kB Cache, UDMA(66)

Any ideas would be greatly appreciated. I've googled this quite a bit and I don't find anything except for the old append = "hdc=ide-scsi" suggestion.

I'm going to keep testing. If I beat everyone to the solution, I'll be sure and post back since the web appears to be void of anything like this.

please post the output of your /etc/fstab for both optical drives.

I suspect one setting is wrong.

Leaping ahead you could always try

/dev/hdc /mnt/dvd (change to suit your system) iso9660 users 0 0

/dev/dvd /mnt/dvd auto noauto,user,rw,suid,exec 0 0
/dev/dvdrw /mnt/dvdrw auto noauto,user,rw,suid,exec 0 0

dvd is a link to /dev/hdc and dvdrw is a link to /dev/hdd

/mnt/dvd and /mnt/dvdrw exist and have the same permissions and ownership.