ProE Virgin - Help Please

Hi, I've just installed R21 for the second time and my cursor seems to be 'flickering' all the time as you move it across the screen. Another problem which I suspect is linked to this is that as I sketch as well as the cursor flickering, then lines I have drawing will not appear on the screen and therefore I cannot see what I am sketching as I sketch. I have not had this problem before, but have had to re-installed WIN200 due to another issue. Can you offer any potential areas of conflict? mouse, graphics card? Any advice would be greatly appreciated, Kind regards, Gordon Smith