This error (Error 1722. There is a problem with this Windows Installer package. A program run as part of the setup did not finish as expected. Contact your support personnel or package vendor.) occurs when customer tries to uninstall the Office addin installed. We suspect the reason could be with the part of code which is used for setting up Ngen for this particular addin's dll.The issue could be with deleting of dlls done with setupNgen. I have no clue as to where the exact source for the error could be i have not been lucky in googling so far. Need your inputs in this regard.