Every now and then, I get a file in my Trash/Garbagebin which just won't go away. I'm guessing there's a file somewhere which my user doesn't have permission to delete, but wound up in the bin anyway?
It's easily fixed tho, it just needs a root user to go into the Trash folder, and delete manually. One can accomplish this with the command:
gksu nautilus /home/username/.local/share/Trash/files
and remove whatever you find.