Once and for all, get rid of the online installer. With the offline installer, add code to completely remove all of the previous version (meaning logs, temp, cache, registry, etc.) prior to installing the new version. This will simulate a Clean Install. Allow the options to retain the Settings (if nothing has changed from the prior version - no new settings, etc,) and the existing Download Queue. Automatically clean out the browser history at the end of a session rather than having to do it manually.
Cats4U
As long as the removing of
everything is optional. Not just the settings and queue. There are plenty of people here, including me, that just rename the StreamFab install folder under Program Files\DVDFab to have the ability to use previous versions and that seems to fix the "Upgrade" issues. I haven't done a clean install in over a year and i have zero localized issues (where it doesn't work for me but works for most others).