"Page not found" error after installing IIS

After you install IIS on a machine that has .net framework installed and you open an ASP.NET page, you will probably get a "Page not found - 404" error.
This is because IIS did not (recognize) the installed .net framework. You simply need to run this command line:

aspnet_regiis -i

You can run it by opening the .NET Framework SDK command prompt or by changing the current directory to "C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727" and run the command. (The path may differ according to the .net version installed)