Issues when running SharePoint 2010 Products Configuration Wizard - System.Security.Cryptography.CryptographicException: Keyset does not exist

Here the encryption key was created on a specific thread which was impersonated under a specific users account. When the .NET Finalizer processes the encryption key while the timer service shuts down it executed on a different thread which is not impersonated - so the key does not exist and you get an exception like "keyset does not exist".
To configure the server to no longer show a dialog when an unhandled exception occurs, use the registry editor to delete the following registry keys:

- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AeDebug\Debugger
- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\DbgManagedDebugger
On a 64-bit operating system also delete the following registry keys:

- HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows NT\CurrentVersion\AeDebug\Debugger
- HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework\DbgManagedDebugger