Green screen on monitor when plugged in via hdmi to display port

I have a MacBook Air plugged into a docking station to a monitor. Every time I wake the mac up the screen on the monitor is green. Plugged into other laptops with hdmi the screen works perfectly. Brand new Samsung screen. If I unplug the connection after unlocking the screen it works occasionally. I took it off the docking station and plugged it in and it does the same thing. Any suggestions what it could be?