In the instruction (which are pretty pants!!) there is a small bit of paper that shows where to put 4 screws and the rubber bit. What is this for?
did you get one? if you did you might have put an extra standoff under the mobo and it is making the case live.
The brass screws under the motherboard, if there is an extra one without a corresponding hole in the motherboard it might be connecting the motherboard to the metal of the case, causing it to become electrically charged. I think I explained that properly. Also is it earthed properly?