I just got back from vacation and while on vacation I turned my computer off for the 5 days I was gone. I just now turned it back on and my desktop picture was changed to the galaxy photo which I know I didn't do because it was a picture of my dog when I left. It was locked in my basement so I know that no one could be messing with me. I also have noticed that my computer is running a little slow, but I don't know if that has anything to do with it? Also I know there is a setting that you can choose to have it change your picture every 30 min. or so, but I checked and that wasn't the problem for desktop 1 or desktop 2.
How can I prevent this happening in the future? Or this an indication of a "deeper" problem?