Check for battery leakage (real time clock battery is NiCad, can corrode and damage motherboard).
It's VERY unlikely to have happened in a week, but if there was some leaky fluid already and it travelled due to movement, could explain it.
Check the monitor hasn't died. Also, I would try removing the Picasso card and running from onboard video - the A4000 could be fine, just a problem with the card.
It sounds very much like a loose connection, but it's especially difficult to find on a bulky, enclosed tower system.
