white zigzag pattern on screen after being woken up

Dell i7-6500 laptop

Lately when I go away from my laptop for a bit and it goes to sleep, it will often wake up with a fine light coloured zigzag pattern all over it.  

I plug into a docking station and the monitor tht is connected to the docking station will also display this.  If I move my mouse around I can see a square moving around the screen.  

I have another monitor that plugs in to the HDMI port.  That one comes up fine.  Using that monitor, if I go to the start menu and manually put it to sleep then wake it up by hitting the touchpad, all three monitors (laptop, docking station monitor and HDMI monitor) will come up correctly and I can keep working.  

However, the other day I was working remotely, and my laptop went to sleep when I stepped away and I could not get the display to come back properly, because I could not see any menus.  I did a hard shutdown.

Any thoughts on the problem?