I'm using Linux Mint 13 Cinnamon for an HTPC. When it originally boots, the desktop icons look like this:

After I come back to it some time later, the desktop icons have changed and they look like this:

Does anyone know why this is happening? Is something crashing?
I realize I'm being kind of vague, which is why I made sure to provide screenshots on this one.
gnome-settings-daemonis getting started up later, and changing your theme. Not sure how to exactly track it down other than to be careful and pay attention to what triggers it. – Jim Paris Sep 17 '12 at 17:48