Anybody encounters this problem? The machine goes in sleeping mode while I'm typing and working on the machine. Sleeping mode = screen black, disks spinning down. By just moving the mouse, the computer jump starts and brings everything back on my screen that was there. This happens 3 times in 5 minutes or once in 3 hours. Unpredictable. We have 2 GB memory, and the apple technician claims the memory is faulty, but the hardware tests says OK.