This happens with my desktop computer too, also with the sleep feature. I have seen other similar reports as well. Asus motherboards might be causing this (got one), but I have also read that Logitech equipment or other USB stuff might have something to do with this. I hope that someone comes up with a solution, as this is quite irritating.
I'm going to see if there's some power-related options in Win7 and bios that might cause this.