Someone brought me a Win 8 system that gives a UAC prompt when moving files within the user directory, say from Pictures to a subfolder or the Desktop. It would seem ownership/permissions have been screwed up. I ran the Tweaking.com repair tool to reset permissions (only option was the entirety of C:\ so it took forever) and it seemed to fix the problem temporarily, but must have un-fixed after a reboot. Malware scans are coming up clean, starting to suspect the user account has been corrupted but need a second opinion.