I'm almost positive that I know what's causing that, and how to fix it. The charger that comes with the unit connects the neutral power line from the wall socket directly with the chassis of the tablet when it is plugged in. Or rather it connects it to what [u]should</u> be neutral. The bottom of the Acer is magnesium alloy, which is a good conductor of electricity, and is part of the chassis.
What I think the problem is in your case is that the "hot" and "neutral" wires to your electrical outlet are reversed, meaning that the chassis of [u]any</u> device you plug into it will be "hot"! So when you touch the bottom of your Acer, you are touching the "hot" wire of your buildings electrical system![:O]
This is a very dangerous situation, and you should have the electrical outlet rewired correctly by an electrician.
I should add: you can check to see if this is the case by merely disconecting the charger from the tablet. If it doesn't shock you when it's not plugged in, the culprit is most likely your electrical outlet. Although there is also a remote possibility that the charger is itself wired incorrectly. RadioShack sells an inexpensive outlet wiring tester that you could use to prove or disprove that the outlet is incorrectly wired: http://www.radioshack.com/product.as...%5Fid=22%2D141