I\'ve VS 2010 and recently installed WCF RIA Services V1.0. For testing I have created a new Silverligh Business project but now every now and then when I rebuild the solution I
Close VS, delete files in c:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\.
Restart VS, Build solution.
By the way; I got the problem after a bluescreen.