Windows Vista Can't Change Desktop

Hello, I have recently had a virus on my computer, I scanned my computer and removed it completly but my wallpaper disapeared, and now when ever I try to change it, it writes this

"This Function has been disabled.
kontact systemadministrator for more information. "

Anyone got any idea what there might be wrong and what i can do against it?? the back ground of my screen is blue right now, when i had the virus it had some weird background like a picture, i deleted it when i was in safemode because that was the only time it would allow me to delete it, and after i did that this happened.

Any help is appreciated Thank you