Desktop is stuck on black....

Hello,
I did an clean install of Vista Business and when i go to set my desktop
image, it stays black.... i have tried going into the gpedit.msc to make sure
privledges were suffice for doing so and still nothing. i am running a dell
optiplex 740 witha gb of ram and 250gb hard drive. i have this system as a
dual boot, i have xp pro on one portion and vista business on the other.. any
suggestions on what i can do to make this desktop work?