If you build Windows 2003 R2 SP2 server for the SharePoint environment and apply windows update, by default it will install the Microsoft.NET Framework 2.0 SP2, Microsoft.NET Framework 2.0 SP2, and Microsoft.NET Framework 2.0 SP1.

With above configuration, you may notice that ASP.NET v2.0.50727 is missing from the Web Services Extensions section in the IIS manager. One of the pre-requisites for the MOSS 2007 or WSS 3.0 is ASP.NET 2.0 must be enabled at the IIS level.

To enable the ASP.NET 2.0, Register ASP.NET 2.0 on the IIS – c:\windows\microsoft.net\framework\v2.0.50727\aspnet_regiis -i using Command line for 32-bit or c:\windows\microsoft.net\ Framework64\v2.0.50727\aspnet_regiis -i using Command line for 64-bit

ASP.NET 2.0 will show up and enabled in the web services extensions section on the IIS manager.