After opening project in Visual Studio, Blend stopped rendering the preview

I have a problem with Visual Studio 2010. When I open any projects created in Blend 4, and simply save it (no mod开发者_开发知识库ification made), Blend stop rendering preview at the design time.

I am using Expression Blend 4. Preview in Visual Studio 2010 is rendered.

So I think, there is some information in the project file, which is added by Visual Studio which prevents Blend from rendering controls. Any ideas of why is that happening?

Installing Beta release of Service Pack for Visual Studio, seemed to fix the problem.