Problem with on screen shapes...

Is anyone able to help out with this problem?
After doing a reformat and installing my software again, I have noticed that squares and circles are showing on screen as Ellipses or Rectangles.
That is that a 400x400 square will show on my monitor as a 200x400 rectangle. (example below:eek: )
This is happening in both graphic programs that I have installed. Xara and Photo Impact.
Obviously, I made a boo boo somewhere in a setting or it is to do with one of the windows updates that were installed but where would I look to correct this.?
Any help here would be greatly appreciated Thank you:)