why can't I change my desktop backgroud from the display tab in the contol panel or from a photo in my pictures. I can however change it from a photo directly from the internet. I am working with windows XP and I also have the program powertoys for window XP.
Most likely powertoys corrupted your system files causing this issue. I recommend repairing the operating system by reinstalling ONLY the system files if you wish to retain your personal files.
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Try fixfault.com to fix desktop pcs.