After wiping and reinstalling my computer (HP m7067c, Intel Pentium 4 w/ HT @ 3GHz, 1GB of RAM, ATI Radeon x1300 256mb, 250 GB HDD, Windows XP MCE and Ubuntu on a separate partition), My CD-ROM drive does not open for either OS. Both can detect them, but it doesn't open. My DVD drive works fine, though. The drive in question is a HP DVD Writer 640c.

Turn the system off.
take a large paperclip and straighten it out as best you can
There is a small hole on the cd drive somewhere. Thats the emergancy eject.
Insert the tool slowly then you find resistance and then push.
That will open the tray
Maybe it is just stuck

If after pushing the emergency eject button and then the actuall eject button doesnt work, then its best to get a new DVD drive and not bother with repairing it. DVD drives are fairly cheap these days, so thats the best way to go.

I used the emergency eject, and the drive opened. However, it was only functional (as in eject button worked properly) before I booted into an OS. I suppose I could get a new Disk Drive, but I want to try the options I have before having to spend money.

If it is a mechanical failure there are no other options
Its a cheap part. About 40 bucks or so
Personally I would replace it

Sorry for bumping, but I forgot to add that this was after I reformatted the disk drive. If it's a software/BIOS/mobo problem, getting a new DVD drive would be pointless.