cannot change wallpaper

this is a very small problem, I was just checking to see if anyone else is
having this. I have installed beta 2 and made sure all drivers are currently
supported for beta 2. I cannot change the wallpaper for the desktop. It looks
like it is going to make the changes but when you look at the desktop there
is no change just the default solid color. If anyone has any ideas they would
be appreciated thankss,