Biz Stuck 2004
The new project I work on now involves using Biztalk 2004. And although I will only be building C# components for that project, I decided to install BizTalk 2004 anyway. That way I can at least run the integration tests myself.
But after installing BT2K4, Visual Studio completely messed up. I tried adding a dataset to my project and Biztalk intervened and tried to edit the Dataset. That obviously failed since it was a new, and empty, dataset. Robert Rijsdijk sent me this link which solved my problem.