I am having the same problem with the Kensington PilotMouse Laser Wireless Mouse. When the receiver is plugged into a USB port, my G5 won't go to sleep. It clicks off and right back on again. Funny, it doesn't do that with my wife's Logitech Wireless mouse or with my wired mouse. I emailed Kensington support. When I get an answer, I'll post it here.