When Visual Studio 2008 is repaired or when a Visual Studio 2008 update is installed, the value of the following registry entry is changed from csproj;btproj to csproj:

    
• For 32-bit versions of Visual Studio 2008:
  
      
  
      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\VisualStudio\9.0\Projects\{FAE04EC0-301F-11d3-BF4B-00C04F79EFBC}\PossibleProjectExtensions
  
      
  
       

    
• For 64-bit versions of Visual Studio 2008:
  
      
  
      HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\VisualStudio\9.0\Projects\{FAE04EC0-301F-11d3-BF4B-00C04F79EFBC}\PossibleProjectExtensions