I just got a Microsoft wireless laser mouse/keyboard combo for my Vista machine. When I had my old Logitech PS2 wireless keyboard/mouse connected, power saving modes worked as expected. Normally, I keep the computer running at full power and have the LCDs sleep after 10 minutes. With the new keyboard/mouse, nothing goes to sleep at all. I unplugged the USB receiver from the computer and it put the monitors to sleep on schedule. I plugged it back in and they woke up immediately. I took the batteries out of both mice and keyboards (all run on same frequency band) and it still won't sleep.