Just moved my step sons PC across his room and when the PC was rebooted we started to encounter the following problem; every now and then the screen goes blank and when it comes back the display/desktop is rotated 90 degrees to the right, after a while the screen goes blank again and returns to normal repeat ad infinitum. All cables and settings appear to be normal, but for the life of me, I cannot figure out why this is happening...anyone help?