On my computer, sometimes when I restart and I get to the part where I pick what account I want to be logged onto, my mouse is frozen and it looks like it is not even pluged in because the light on the bottom is not on. I have a laser mouse and it plugs into the USB Port. It has been like this for a while an I do not know why it started. They only way to fix it, is to restart the computer again by holding the power button on the tower.