Unperforming wallpaper

After installing Vista, I cannot install picture wallpaper under my name, but
I can change the colors of the background. However, everyone else logging
onto my computer can put pictures on the background.

How can I fix this so I can put any photo on the background. When I open up
the display tab and double click on the pictures, it does not take....unlike
the solid color selections.

This is driving me nuts...that and my Dell all in one printer does not work
with VIsta and no new driver is out yet. (Seperate issue)
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Thanks!
Rocky