ok, got that wrong, this old version of MADVR didnt have use DIRCT3D11 tick, it turns out this is actually whats causing the problem, eveything was ok until I ticked that, so there are now three ways to stop this problem,. 3 bits of evidence.
- Put my TV in PC mode - problems goes away
- turn off refresh rate switching and play movie at 60hz
- turn of use DIRECT3D11
I might be even more baffled now
