I have an issue, my monitor flashes and goes black for a couple of seconds. Yesterday, it went black as usual but didn't go back to normal, instead the monitor displaed a "no signal" sign. I shut it down and turned my PC back on, it started fine but the monitor still didnt display anything. I have found a solution to this which was unplugging my power cord, holding the on button for a few seconds and plugging the cord back in. This works and I am now able to start my PC and the monitor works fine,but the screen flashing problem still hasn't gone away. Any suggestions what might be the problem?