Parser Error Message: Execution permission cannot be acquired.

[Goffin]

I get following error on one of my websites:

Server Error in '/DotNetNuke' Application.
________________________________________
Configuration Error
Description: An error occurred during the processing of a configuration
file required to service this request. Please review the specific error
details below and modify your configuration file appropriately.

Parser Error Message: Execution permission cannot be acquired.

Source Error:

Line 256: <add assembly="System.EnterpriseServices,
Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
Line 257: <add assembly="System.Web.Mobile,
Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
Line 258: <add assembly="*"/>
Line 259: </assemblies>
Line 260:

Source File:
c:\windows\microsoft.net\framework\v1.1.4322\Config\machine.config
Line: 258
________________________________________
Version Information: Microsoft .NET Framework Version:1.1.4322.2032;
ASP.NET Version:1.1.4322.2032

I allready tried reinstalling .NET, IIS, recreating the website in iis
without any success. Has anyone an solution for this error? It would be
a great help.

Thanks

Christophe