Lately I have been having constant system freezers. I'm using os 10.4.11 on a powermac dual 2 ghz, 2.5 gig ram. The system either totally freezers, mouse light active but not the keyboard. Or... the system freezers then the screen gets a grey tint that swipes down from top to bottom and a black box window in the middle of the screen with white text telling me to restart. The freezers are random. Sometimes I'll get several a day or I might go a 1-2 days at the most before it occurs. I've already run an extended hardware test and it showed no faults. Repaired permissions, no probs there. Can anyone offer any suggestions or advice?