Openroads (MX SS3) very unstable

I am a traditional MX user and I've started playing about with Openroads. The problem I keep getting is the graphics driver kernel keeps crashing apparently which results in the screen going black until it has recovered. On a couple of occasions it hasn't recovered altogether and has required me to restart my computer by force. It doesn't seem to happen at the same point but I was working mainly with corridors.

My graphics card is NVIDIA Quadro 4000 (Driver WDDM 1.1 version 8.17.12.7628) in a DellPrecision Workstation T3500 with Windows 7 pro 64-bit (6.1)

Does any have any ideas what it could be or how to solve it?

Thanks,

Ken