I had this problem on my first PC. Someone on this forum advised me to pull the cable from the back of the PC and check the connection to the cable going to the front. I pulled the cable by removing one of the top lights, unhooked/reconnected the two cables, taped them to make sure the connection was tight and stayed tight, and the monitor worked perfectly thereafter.
spoke to Kermit today and he said it was the camera that was the problem.
I will check out the cables to the camera and monitor. All wiring is behind the TV up front which I do not know how to get into.