Deaktop shrinks

Hi all, I downloaded and installed Casino-on-net which runs fine but what
i`ve found is that if I play the game on full screen(it opens by default to
minimized 1/2 screen), is that when I exit the game the desktop has shrunk
ie: there`s a black 1/2 inch boarder around the edge and any applications I
open are all the size of the desktop. I`ve checked the display properties
and nothing seems to have changed. when I reboot all`s back to normal. Any
ideas on what I can do to resize it back to normal without rebooting.
Thank and happy new year
Kim