I've been following the instructions at http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dv_vstechart/html/ol03csharp.asp word for word, but I'm having a problem in my OnBeginShutdown() event. Basically, applicationObject.ActiveExplorer() is null, so I obviously can't remove my toolbar button from it. Is there something else I should be doing?