The server may not have the proper version of ASP.NET registered. Please see the appropriate steps below to register ASP.NET with IIS on your server:
Windows Server 2008:
Click Start and type cmd in the search. Right click cmd.exe and choose "run as admin". Browse to this directory.
Windows\Microsoft.NET\Framework\v2.0.50727
**for 64 bit Server 2008 the path will be Windows\Microsoft.NET\Framework64\v2.0.50727
then run the following command.
aspnet_regiis -i
Then restart IIS and the web page should load.
Windows Server 2003:
This can happen when IIS (Internet Information Services) has been configured incorrectly. Please make sure that ASP.NET v2.0 is set to "allowed". To do this, click on Start > Administrative Tools > Internet Information Services (IIS) Manager > Expand the instance of the Relay website > Click on "Web Services Extensions". Make sure that ASP.NET v2.0.50727 is set to "Allow".