A Cause To The No Response Of The Expression Blend 4 When Open A WPF Solution

I encountered a problem that the expression blend 4 did not work with the information “no response” when I was trying to import a solution created recently. As can be seen from the captured picture below:

Nothing appeared to be wrong and the Blend 4 worked well days ago.What is the most strange thing is that other solutions can be opened smoothly. I just get confused and tried lots of methods.I discussed this problem with some people who are experienced in programming.I even asked for an explain in Codeproject and Microsoft Expression website. However, no right answers.

I came up with a solution by incident. As the solution can be opened successfully in visual studio 2010,I had a feel that the reference included in this solution can cause some problem. I have ever added the Adobe Reader library in my project. So I deleted the WPF page and the references in my project. Blend 4 ran well like a miracle. Although I still do not know the details in windows system ,I am happy to have solve the problem.Waitting for past masters’ tips.