Power Problem

It seems as though my power button does not work sometimes. If I push the power button, nothing happens, I then unplug the main ATX power connector and plug it back it and then it will power up with the power button. Is this most likely a faulty power supply? Also, it seems that my BIOS drops the Primary Slave hd, and it forces me to manually enter it in the BIOS setup. What is going on here. Same problem, two different?