While installing SQL Server 2008 on Windows Server 2008 R2, i got following error message at initial stage in process.
Windows was up to date and required version of .Net framework was installed on it. Opened Server Manager for Windows Server 2008 and clicked on features in left panel. Then by clicking Add Features link in right panel another panel was opened with several features available there for installation. I checked the box for my required .Net framework feature and Clicked on Next button to proceed with the installation.
The .Net feature was installed and SQL Server 2008 installation ended successfully.