There is something that I am soon going berserk with my SP4: Once or twice a day suddenly - in the midst of some activity, e.g. writing some email and out of the blue the SP is not reacting any more to ANY input: No mouse, no keyboard, no touch, NOTHING! Also just waiting for a minute or so doesn't help. Switching off/on still works, but doesn't change anything, when it comes back on it still doesn't react to any input. The only thing left in such situations is a hard-reset, i.e. pressing the power button for 30 seconds or so. But of course that means loosing all unsaved work and having to reboot again. Gggrrrr! One soon day I am going to slam this thing against the next wall! Any idea anyone what could cause this?