One of my guys had the same problem, and it turns out it is related to the Display Settings under Windows 7. He had his set to Larger - 150% (Control Panel - Display - Make Text and other item Larger or Smaller).
Set it back to Smaller - 100% default and it will go away. Drove us crazy for a few weeks trying to figure it out. All his Forms and any items on the forms (Grids,textboxes, etc) got bigger and bigger each time he opened them. At one point, a simple web form was 55000, 43000 !
rob