Yesterday I was trying to install SQL Server 2005 on windows 7. During installation a popup error dialog shown with this message: The SQL Server service failed to start. For more information, see the SQL Server Books Online topics, "How to: View SQL Server 2005 Setup Log Files" and "Starting SQL Server Manually. Here is the captured screen: But in books online there was no useful information! After some hours googling, I did not found any useful information and at 3 o'clock of midnight, I was scratching my head! Believe it, I attempted to install SQL Server more than 15 times with different manners (with command prompt & parameters and else). Eventually I found the resource of problem, that was "BitDefender Internet Security 2010"! After uninstalling BitDefender Internet Security, I installed SQL Server 2005 and then reinstalled BitDefender. Just that! Problem resolved. Conclusion: After installing a new version of windows and it's requirements (like IIS and language specifications & else), first install the SQL Server and the Visual Studio and then other applications.Hope be helpful.