i was typing away last night and the ibook (4 yrs old) froze. I couldn't control anything on the mouse, etc. I restarted and got a blue screen. Then turned it off and tried again this morning. It went to the sign in page, which was good, then it was unresponsive to scrolling even when I plugged a mouse in. I tried to use the start up disk holding down the c key but blue screen again.