WORST always on top!

hey, i have this problem with my program windows…
if i have more than 2 or 3 programs open at a time, often ‘always on top’ will magically bestow itself upon one of my programs, and i can’t turn it off. the result? i have to exit that program.
it’s not a huge problem, but it’s been a full year, and it’s really starting to get my hackles up. anyone know how to make it go the hell away?