Sounds like a motherboard issue right enough.
Spent around 30min trying to track down a motherboard for you but came up blank.
Only thing I can suggest is contact Acer and see how much of your life savings they want for a new board.
Did find plenty forums / threads of people complaining about similar faults though so maybe worth trying another board if possible.
Whats the make/ model of the board? possible to upload a pic of it?