Last year I wrote a quite popular article HOWTO: Troubleshooting Visual Studio and Office add-ins, to diagnose many common problems with add-ins for Visual Studio or even Office. One invaluable tool to diagnose a whole range of problems with an add-in setup or the Add-In Manager of Visual Studio is the Process Monitor (ProcMon) tool, formerly developed by SysInternals and now part of Microsoft Technet. My MZ-Tools add-ins for Visual Studio (all versions), VB6, VB5 and VBA are installed and registered smoothly for tons of users every week, but from time to time I get a support incident about the setup failing due to something wrong on the user machine and I diagnose the problem requesting the user to run the tool and sending the trace back to me. While the Process Monitor tool applies to any developer, not just add-in developers, not everybody is familiar with it, so I wrote this article to explain how to use the tool and to refer my users to it. As an example, I will show why Visual Studio 2008 fails to recognize .addin files when stored in the folder “%ALLUSERSDOCUMENTS%\Microsoft\MSEnvShared\AddIns” that was introduced by Visual Studio 2008.

HOWTO: Using the Process Monitor (ProcMon) tool to diagnose Visual Studio add-ins problems
http://www.mztools.com/articles/2008/MZ2008024.aspx