Strange random lines on random frames

[gummipolarbear]

Hi,

I'm doing a render with Vray and Phoenix FD using VRay Environment fog for the horizon. I am getting these random lines and boxes every 10-15 frames and not what causes it. Anyone else have this issue or know what causes it?

Thanks

[gummipolarbear]

Updated the graphics card driver and issue seems to have gone away now/