if you removed any usb devices, and plugged them into different ports and tried to boot the system up, plug them back into the exact same ports. I went to move my pc, had two devices plugged in (a xbox 360 game controller, and a logitech unifying receiver for my wireless mouse and keyboard) to the front panel connectors on my system. when I moved the system downstairs and turned it on, i had the exact same issue. But putting the devices back into the same ports solved the VGA problem for me, oddly.