1. After install, my registration (regkey) of 3.x was removed (I got a 30-day trial period). I have not seen info on the site during download that re-registration was necessary.
2. But, apart from that, when I click the `Register...` link from the Help menu, the application freezes, I must close it down then from Windows Task Manager. Via Help - About... and then the Register... button it is the same. Have tried multiple times. Also rebooted.
FYI I am using XP Pro SP1 on a laptop.
When you install 4.0 version, it detects whether you have registered 3.x version and if so, the first screen of the installation program warns you about that.