Does the BIOS identify that there is indeed a CDROM drive in the computer? I know sometimes when I swap out CD/DVD rom drives I forget to set the master and slave jumpers. Check those out and make sure they are set correctly. It also seems like you have alot of stuff in that computer. Do you have a PCI IDE card or are you running all these devices off the motherboard IDE controller (1 hard drive and 3 Cdroms)? Most people with more than 1 CDROM drive also have a few hard drives so that would usually require a separate controller. You can try and swap the Cdroms that arent working to the PCI Card Controller, that sometimes helps.
If none of that works this problem could be virus related. There are viruses out that screw with your dlls. That would certainly screw up your computer and maybe, depending on the type of virus, only effect your CDROM operation. Update AV and do a full system scan.
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