I have this problem with my Dell, where in when I boot, the BIOS does not show any of my hard drives (two) or my CD and DVD drives. I have opened the case and tried plugging in using different cables but none works. The only success I have is when I do not connect my primary hard drive. When I donot connect the primary drive, My CD and DVD drives show up as secondary drives in the BIOS but none of my hard drives are seen in the BIOS. The moment I connect my primary hard drive, none of them are seen in the BIOS. Is this a problem with the mother board or the hard drive itself. The system was working perfectly before this problem has happened. Any help is appreciated.