I try to add a new web application in sharepoint central administration and get the following error message:
Failed to apply web.config modifications to file 'C:\inetpub\wwwroot\wss\VirtualDirectories\9675\web.config'. Failed to apply a web.config modification to file 'C:\inetpub\wwwroot\wss\VirtualDirectories\9675\web.config'. The specified node "configuration/system.webserver/modules" was not found in the web.config file
The same error appears when trying to run any Shell-Command that changes something in the web.config. I already tried to do a repair-installation of sharepoint with no afford.
Any idea what could cause this error?