power supply - Electric shock with plugged in VGA cable

Possible Duplicate:
Why would I get an electric shock from a VGA cable connected to an LCD monitor?

Similar to this question I got shocked today with a new computer I just bought. How is this possible and how can I prevent this?

• There is no power cord in the PC


• Only the VGA cable is plugged in, tested 2 different flat panels


• When touching the case and my metal desk, I feel a shock.


• Unplugging the monitor cable from the pc stops the shocking (obviously)


• unplugging the power cord from the monitor stops the shocks (obviously)


• power-outlets are not grounded, and there's no grounded outlet on this floor (top floor)