cd-rom not recognized

i have a computer that at startup detects the cdrom as secondary master, which is how it is set, but when i go into my computer it is not there, the c drive has been partitioned and there are 3 other drives showing up, d e and f, when i change the boot sequence to boot to the cd it does just that, but it wont show up on the computer! any help with this would be greatly appreciated.