Booting problem in acer 4520

Plug in the power cord and wait a few seconds. Then click the start button again and again until it turns on. It will say windows did not shut down correctly, do you want to start windows normally? Hit yes.
What happened was you ran the battery so far down, that windows freaked out. My wife did this on our 4520 a few times. She thinks the computer is shut down and closes the screen. But it was not shut down completely and it went into stand by mode. Well a few hours later, the battery is so dead that windows crashed out.

*********** board needs to be replaced