A friends computer all of a sudden stopped working a week ago: you would turn it on, see nothing on the screen (monitor says no input signal) and then it would start beeping viciously until you turned it off. I went over to fix it and had no idea what to do, so I took all the expansion cards out and re-inserted the memory. Now it boots up with all the expansion cards back in and everything looks good, except the mouse doesn't move and the keyboard has no effect. I am using the friends mouse on my comp right now so the mouse (and I'm sure the keyboard) is fine. Help?