We have several customers who use a Word COM Add-In of ours.
The Add-In has worked fine in the past, but now refuses to start. It shows un-checked on the "COM Add-Ins" dialog accessed from Word Options, with a message talking about a runtime error during startup. StartUp Behaviour is 3 and stays as 3.
The Add-In consists of a shim written in C++ and a .NET Assembly written in C#, but it doesn't get as far as the OnConnection in the .NET assembly - I know this because that code writes to the Application Event Log, saying the Add-In is starting up, and there is no such message in the App Event Log. There are no relevant entries in the Application Event Log, so I'm at a loss as to what the problem is.
This only seems to be a problem with Word 2007 (32 bit) running under Windows 7 (32 or 64 bit).