Got a second monitor for my Dad's Mini. Primary is connected with HDMI to DVI adapter [came with the Mini], and secondary is connected with a Minidisplay port to DVI cable. When I put it to sleep, it comes on again within a few seconds with a message saying 'DVI Input'. Happens even if the power to the second monitor is switched off, but does not happen when the cable is physically removed from the Thunderbolt port. Anu suggestions?