Help ! my work machine sw2010 display has gone jerky and hestitates now- !

I had to move sw2011beta from one drive to another, so last night I did an unistall and re-install to the new location. It seems to work ok, but i havent used it with a vengeance yet so i am not 100% sure that it doesnt have the same problem. The original drive was the demountable backup drive, and it is no longer connected to the system - we have had to use it elsewhere-

However now my sw2010 sp4.0 starts up fine, but after 5-10 minutes use it starts to bind up, the display reaction time seems to start stuttering or jerking whenever zooming or rotating-

I have run a repair through the 2010sp4 install manager-

Any clues?