Mavericks keeps changing wallpapers of additional desktops

Does anyone know why Mavericks keeps changing wallpapers of additional desktops (spaces)? Wallpaper of the main desktop (#1) stays the same, but a wallpaper set to desktop #4 may suddenly "migrate" to desktop #2, and so on.

After resetting wallpapers, everything would work normally for a while, until wallpapers migrate again. I have to reset them the way I like every two weeks or so. Since I use different wallpapers to distinguish between different desktops (spaces), it's very confusing when they randomly switch places.

Thanks

 

I think I have better understanding now about what's going with changing desktop backgrounds. Actually, backgrounds don't change. What changes is the order of the additional desktops. Somehow desktops #2 and #3 switch positions. I can restore it back through mission control, but I would like to know how this happens in the first place. I only use Control+1, Control+3 and etc to move between desktops, but in the process somehow their order gets changed.

 

Is there a way to reset caches and saved states for Spaces? Thanks

 

Thanks. I'm also wondering if there might be some keyboard shortcut for changing the order of spaces that I hit accidentally.

 

Thank you! That explains everything.