Hi I have a powerbook g4 1.67 17" High res, and I have a problem with my computer freezing. I have to reboot it, but when I reboot it, it doesn't post and searches for a disk in the superdrive. The only way I can get it to work again is by forcing it into open firmware, reset everything, then install leopard onto it again. I've had to do this twice now, with 2 different sets of memory: 2x512 and 2x1gb. Could it be a hard drive problem, or is it the logic board? I also ran apple service diagnostics and hardware tests. Everything checked out fine.