Lately, the setup of a plugin for Enterprise Architect failed with the error message:

This advertised application will not be installed, because it might be unsafe. Contact your administrator to change the installation user interface option of the package to basic.

Oops – what does it mean? OS was XP, user had full local administrative privileges. So what could have caused the error?
Google says, it’s because of a broken uninstall of the previous version. One should delete the installer’s registry keys manually.

Other option: start the package by using the following commandline:
msiexec /i MyApp.msi /qb

Parameter /qb starts the GUI in basic mode. Whatever the difference is, solves the issue.