Windows cannot open this program because the license enforcement system has been tampered with or become corrupted

Question

I have a problem with my website. I recently upgraded the website from Framework 2.0 to 4.0. Now when entering an URL on the website. I receive this error message

See screenshot of error here: http://www.bilddump.se/bilder/20150215151938-195.252.32.111.bmp

The beginning of error is: [Win32Exception (0x80004005): Windows cannot open this program because the license enforcement system has been tampered with or become corrupted System.CodeDom.Compiler.Executor.ExecWaitWithCaptureUnimpersonated(SafeUserTokenHandle userToken, String cmd, String currentDir

I have looked in the web.config file and my system.codedom tag are empty like below. I might wonder if they need to be set in a correct way in framework 4.0. If that is causing the problem I wonder what the correct system.codedom tags looks like?

  <system.codedom>

  </system.codedom>