When running a new installed Sitefinity site I got the following error:
Could not load type
' from assembly '
System.ServiceModel, Version=188.8.131.52, Culture=neutral
I noticed this was a issue that was reported in the forum but only with the beta 2 version of Sitefinity 4 (http://www.sitefinity.com/devnet/forums/sitefinity-4-x/general-discussions/could-not-load-type-system-servicemodel-activation-httpmodule-sitefinity-4-0-beta-2.aspx
I have the same error in Sitefinity 4.1.
The solution that was mentioned in the beta topic solved my problem as well:
use aspnet_regiis of .NET framework 4 to reinstall .NET in IIS.
Just wanted to post this, it might help someone else.