Mac cannot delete file The item image212_tmp1987326278 can’t be moved to the Trash because it can’t be deleted.

I don't know how that file appeared on my desktop but as I try to delete it I get the above error. Does not let me rename, move it or use "Get info" either.
I recently had the same problem, and fixed it by opening Terminal.app and entering killall Finder. This effectively resets the desktop icons.