If you run the Single Player Server, make sure you connect with the Single Player Client (MMCCIII). If you have installed the Multiplayer Client using ModSwap, then uninstall it, and you will return to the Single Player Version which is the default installation.
Thanks guys, I always used the quick start for windows option to run the game as apposed to the Cross of Iron command center option, so I had never seen the MMCCIII client option before. I've got it working fine now, so thanks again.