Why wont my hard drives activate

Hello,
My PC locked up last night and I had to shut it off. When I went to turn it back on I get nothing on the screen. Both cd-roms activate and run through their check sequence, but then the system wont go any further. It wont check the ram memory or go through the bios check. It has done this before, but after a couple minutes it would boot and run normally. Now I let it set until this morning and it still does the same thing. My father-in-law says that the back up battery is dead and that would cause this, but that does not sound right to me. Please help!