Starting a website got this error.
It means that Authentication level in IIS is not the right one .
It also means that probably you didn’t add all the needed features to IIS.
go to :
Start –> Control Panel –> Programs –>
Turn windows features on or off –>
Internet Information Services –> World Wide Web Services –> Security –>
Now you choose 3 new options :
Basic , Digest and Windows Authentication .
Start –> run –> inetmgr –> Default web site –> features view –> authentication –> double click –> you can see the features you installed –> enable Windows Authentication .
That will resolve the problem.