neillm, my guess-from-1,000-miles-away is that the main board is broken/defective. I'd check with wherever you bought it to see if they'll replace it.

utdrmac, I've not heard of any firmware updates for the Cube. I word it that way because while I've been following these things since their release, it's always possible that there is something out there. Communication and documentation from ASICminer are scant as a rule.

At the very least, I've not seen mention of a firmware update in this thread.