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?

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