I realize my post is several months past the time this question was
originally posted, however I just ran into this problem myself on a
Windows XP system.

I found the culprit to be a program named Wallpapertoy.exe. I don't
know how/where it was installed from, but when I killed the process my
wallpaper stopped changing on me. In control panel/add remove programs
I also found the application and removed it. Problem solved.

Regards,

Terry


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terryj