My g5 tower dual processor can't get past the grey screen when I start it. The computer turns itself off. It was running really slow yesterday then I got a kernal panic. Now won't start up. I tried resetting the pram, resetting the pmu and starting it from the leopard disc. I wasn't aware you had to hold the keys down for a pram reset until the comp starts itself, I was holding it for about 12 minutes and I heard the chime sound about 4 times then I let go. I got an error when I ran disk utility. Didn't really say what the problem was. It's a brand new harddrive. Been working great for months now. It's a somewhat old comp had it for close to 6 years. My theory is maybe the battery needs to be replaced? thanks. found this handy guide, going to try some of these tonight when I get home.