If you have already performed the emergency repair process and the computer still does not operate normally, you may want to do a repair/in-place upgrade of the existing installation.

An in-place upgrade is the final alternative before you have to reinstall the operating system.

Note that it takes the same amount of time to do the upgrade as to reinstall the operating system. Also, some of your customized Windows settings may be lost through this process.

Source: How to Perform an In-Place Upgrade on Windows Vista, Windows 7, Windows Server 2008 & Windows Server 2008 R2

http://support.microsoft.com/kb/2255099