If players have lots of stars their name plates take up more space on the screen if they play at position 3, 4, or 5. Players with unusually long usernames take up more space if they play at positions 1, 2, 6, or 7. In either case the map is smaller. If any of these players get eliminated the map pops back to a bigger size. Also the little blue ribbon that marks the biggest player may also affect map size when it moves around.

This is really only a problem with Internet Explorer (possibly Netscape and Opera too, I wouldn't know); hop on the Mozilla Firefox express, young Knooblet.