We have a Dimension 4600 and the display suddenly stopped working.  We were using the DVI cable and switched to the blue cable with the same results.  I disconnected all the cables and the monitor comes up with the floating self test just fine.  We've tried hooking it up as an external monitor to a Lattitude 620 and go the same results.  I tried to get to the monitors Main Menu, but nothing happens when I push the button.  Can run anything with the desktop because we don't have a spare monitor.  Any suggestions on what to do next?