Uninstall the game.
I've just finished the DLC, and I didn't have this issue, nor has the game's wiki page reported this.
Well, thanks for that.
OK - I've unistalled the entire game by deleting all local content on Steam.
IT DID'NT WORK!!!!
Ideas appreciated.
[Edited by Rick_Terminal, 9/9/2010 6:20:18 AM]