Windows Me fails to shut down

A user of mine uses a notebook (ACER TravelMate 351) running Windows Me. About 5 times out of 10, it fails to shut down. Usually all applications will be closed and then a blank (black) screen with a flashing cursor will be shown. Most of the times,after the user presses and holds the power button for about 6 to 8 seconds, the notebook shuts down. However, sometime, we have to remove the battery pack in order to do so.

Any suggestion?