Are you sure it's not just the screen freezing?
I recently fixed a laptop that they thought had crashed, but the screen would simply stick (meaning you cannot see mouse movements or keystrokes)
I think the problem turned out to be the graphics card in that case. Good point to start though.
Always remember my number 1 rule for laptop repairs:
Acer are shit.
My GF had one (she chose it) and had nothing but problems. She's doing much better now with the Compaq Presario that
I picked for her