Hard drive boots in Master/Slave mode, but not by itself
I have two hard drives installed in my computer - a 120GB one and a 250GB one. Both have Windows installed on them. When I set the 250GB to Master, and the 120GB to Slave, the computer boots normally, and everything works. Now, I don't really need the 120GB drive, so I want to unplug it and just keep it inside the computer. I unplug the power plug form it, and the ribbon cable, leaving the jumpers in the same place on both drives. Then I try booting up the computer, and it says "No operating system found!" When I go into BIOS setup, with only the 250GB drive plugged in, it doesn't detect any hard drives at all. What am I doing wrong? Thanks for all your help.