Hello, rencently my iMac g5 2.0 white, just randomly shuts off, i have no sleep timers, but in the last 2 weeks its just shut of while i am doing something. I have seen no, pattern its just sometimes it just shuts off. Any ideas what is going on? Also my doc on the bottom seems to get smaller, and then when i re size it back to normal ,it cant go back to that original smaller size. very weird activity. any ideas..?