You need to set up a udev rule for the cdrom.
I had the same issue with a usb hdd with three partitions. At times when I would plug in the drive it would have different mount points and/or different device label.
So I wrote a rule for it and also added a fstab entry depicting who could mount the drives and a statc mount point.
That solved all my problems.
See the following tutorial on writing udev rules.