[ubuntu] Weird one with CD/DVD drives

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http://ubuntuforums.org – Anybody want to take a crack at this one? I have a Dell Dimension 4600. Installed two drives from a Dimension 3100, running Windows XP. Installed two CD/DVD burners. Both were working previously. Got it up and running and then set up a dual boot with Ubuntu 11.10. Everything fine EXCEPT the machine will NOT recognize the CD drives. They don't show in Windows Device Manager, they don't show in Ubuntu. They don't even show in the BIOS setup. At one point I had one drive working, after doing a Regedit trick I found online, but it disappeared again and hasn't come back. Both jumpers are set correc (Hardware)