forgot the code DO!
it's pretty sure it's down to fstab. check where /dev/dvd and /dvd/cdrom point to, it's likely you'll want to swap the links around. try ejecting the drives...
if that opens the cd drive then you'll want to swap the links over.
ls -l /dev/dvd /dev/cdrom
lrwxrwxrwx 1 root root 8 Oct 25 19:46 /dev/cdrom -> /dev/hdg
lrwxrwxrwx 1 root root 8 Jan 24 22:58 /dev/dvd -> /dev/hdf
ln -sf /dev/hdg /dev/cdrom
ln -sf /dev/hdf /dev/dvd
the /dev/dvd and cdrom files are only pretend, and can safely be overwritten.
acutally tho, you're on MD81, which uses devfsd instead of a flat system, which might make that not work, in which case wiring up the devices backwards in fstab should do the trick, i just think that's a little bit of a cludge.