Adamskii pointed this out to me a week or so ago:
Now, when he sent it to me, it wasn't occurring within IE or Firefox on my PC, so I presumed it was temporary.
But, today I noticed it... so School Boy Error to me!
I'm guessing it's to do with the content itself, as it's making the theme a bit offset. Though what with all the php-hacking I've done, it's probably a result of my work.