Well, I saw this on a LOT of friend's journals: four odd little boxes at the end of a post. Turns out this was from some messed up flash exploit. So check your posts and make sure it didn't hit YOU!
Flash exploit targets your most recent post with malicious code.
LJ's shut down a lot of it's flash stuff so it's not keeping infecting, but you'll wanna remove that code I'm sure anyways.