I recently upgraded from Windows 7 to Windows 10 and after that I couldn't run Paint.NET anymore, and when I tried to re-install it I got the famous 1603-error. Also, I couldn't uninstall it (kept getting an error message).
The solution for me turned out to be uninstalling Paint.NET using IObit Uninstaller - http://www.iobit.com/en/advanceduninstaller.php
After uninstalling Paint.NET using it, and also allowing it to remove all the posts related to Paint.NET in the Windows registry, I could re-install Paint.NET without any problem.
