I lost video playback. Can play the video in Bin, but when drag it to the time line or in Source monitor, there is audio but no video.

Can drag to time line and same. My Source record windows are grey, not black.

Any ideas. 

I did uninstall quiktime, but have reinstalled it and then did a full unistall/reinstall of MC

Are your video tracks enabled for monitoring?  My monitors go grey when I disable video monitoring.

Yes, that's the first thing I checked.

gpu driver maybe?

try installing the nvidia driver that comes with your avid version.

Thanks, all sorted, swapped monitors around, so no 1 is loading as primary and all good.

Amazing.

Hugh