Computer powers on and shuts off after removing DVD Drive

I'm in the process of moving some parts from my current system to another computer. I removed a DVD drive and a hard drive from my computer, and after pushing the 'on' button, the computer powers on for a few seconds and then shuts off. I don't understand what could possibly be causing the problem. I have two hard drives and the hard drive I was removing wasn't even my primary hard drive. I've also used the computer in the past without that hard drive, so I know that can't be the problem. I think the lack of disk drive is what's causing the problem.

Upon removing the DVD drive, I also removed the SATA cable from it that was connected directly to the motherboard. Could the removal of that cable be causing the problem? Also, on second thought, the hard drive I removed was connected to a PCI Express SATA card with a SATA cable which is still in the computer. Could the unused SATA card sitting in the computer be causing the problem?

Thanks for all the help you guys have given me. -.-

I just removed the SATA card and powered it on and the same thing still happens. I don't understand how this is happening, all I removed was the DVD drive and my secondary hard drive. It should still be working.

I also tried some 'voodoo' and plugged the SATA cables back in, letting them hang without connecting to anything. Nothing happened. Could the power supply have been damaged while I was moving the parts out?