My mac book pro is connected to a monitor via a display port cable. The connection worked perfectly yesterday. but today the monitor says " no signal detected". When I connect with the cable, the monitor wakes up and the mac book shows the monitor settings. So somehow they get a signal. I restarted with and without the cable connected, I set both to sleep, I restarted with another user, I made sure the cable is plugged in... Does anybody have an idea what to do next? Thanks!