done

Fixed!
Also, now I know how to keep my drivers up to date (also had to visit nvidia website for their drivers)
Thanks mate!

1st rover mission: relaunched save game, drove rover off platform, major error wheel 5 - dragged wheel until I stopped rover to take a photo, rover stuck.
went to menu, changed physics sim to max - no effect, still stuck. changed physics to min - rover moves off dragging wheel (yay!). Drove for a while, got stuck while driving, changed physics to max (no effect) then back to min and drove off again. stopped on rock to take photo of Victorias rocky edge, tried to drive off, rover stuck. changed physics up then down, but this time no effect at either end of physics slider. Drove in a circle (wheel 5 stuck to ground, rover rotates around wheel) and fell off side of rock. broke panels and instruments off, was hoping to break wheel off. rover upside down, wheels still turning except wheel 5, but at least now I had good reason to go nowhere as I was upside down.

forgotten info from original post:
Platform: PC
OS: Windows 7 Home Premium SP1