Error "Error in registry for extension 'Exchange Extensions;?'" (4328480)

You receive the error: "Error in registry for extension 'Exchange Extensions;?'" when trying to open an email from a Source or Target Storage in Recovery Manager for Exchange.

The cause is corruption in the registry at this location: HKEY_LOCAL_MACHINE\Software\Microsoft\Exchange\Client\Extensions

Microsoft has published an article about this very issue which you can find here: http://support.microsoft.com/kb/823633

This Microsoft article involves making modifications to the registry and Microsoft recommends that you make a backup of the registry before making any modifications.