Visual Studio 2005 Tools for Microsoft Office System Client TroubleShooter
Developing VSTO applications can be fun and certainly very productive. But just like all other software development it isn't without its own share of problems.
To help solve some of these problems Microsoft PSS has released the VSTO 2005 Client TroubleShooter tool. Maybe not guaranteed to solve all your VSTO problems but another tool that gives you some more information.