Generally, this error occurs because the Microsoft .NET Framework 4.0 configuration for ASP .NET has been damaged. You must repair the .NET Framework 4.0.30319 version at a command prompt.
A quick fix, do:
%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -i
OR
%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -i