I had put some music on some friends MP3 playing using windows media sync. Bout time I got around to syncing some music for my DX even though I had a hand full of music I had put in the sync list, all the music I had sync previously from the other MP3 players were added along with almost everything else in the PC.
I never known this to happen but its like in the background it had to autosync these files everytime I hook it up along with any new ones. I had to play with these options erase all the music on my DX and start over again.
What I'm saying is maybe at your last session of moving one photo they all piggy backed along somehow.