I have a new HP Pavillion dm4-1160us Entertainment Notebook, 64bit running Windows 7 Home Premium SP1 4gb of ram. I am trying to set the computer up for my wife and I to share. I have set up two users with administrative rights. When I switch between users, sometimes all works well, but at other times there are no users shown on the screen after requesting the switch, just a blank screen. Alt-Ctrl-Del has no affect. I end up doing a hard reboot to get back to login choices. Does anyone know of a solution to this problem.