swert, Sleep timer running out at end of a frame wouldn't cause hibernation or sleep either one, Has to be idle for x number of minutes before sleep overtakes the computer, Kinda like us, we have to be sitting still and relaxed for certain amount of time, same principle.

far as a brown out, its possible, if your house didn't lose power but wasn't getting the full amount power, it would cause something similar to running a computer that Has a PSU that's in adequate and would run un stable ( Theoretically.

G-man