Another problem that can happen to an uninstaller of add-ins for the current user (not for all users) specially in Visual Studio 2005 (which require admin rights):

PRB: Uninstaller of add-in for current user fails if Visual Studio set to execute as administrator
http://www.mztools.com/articles/2011/MZ2011022.aspx

This issue affects these articles:

HOWTO: Create a setup for a Visual Studio add-in for the current user (not requiring admin rights) using Inno Setup
http://www.mztools.com/articles/2011/MZ2011018.aspx

HOWTO: Create a setup for a Visual Studio add-in for the current user (not requiring admin rights) using using Windows Installer XML (WiX)
http://www.mztools.com/articles/2011/MZ2011020.aspx