I've been using Vista all year & I've had some problems, but nothing like you are talking about. First of all, if you're going to upgrade, you should
not Un-install first, but just upgrade. You should also SAVE all your downloads in your Download folder so you always have whatever you need at any given time. I have gone back & forth from 4.0x & back to 3.321, then up to 4.03, to 4.05 and now to 4.06 and have not had any trouble with registrations
. You can't blame
everything on MTU.
MTU had problems with 4.0 too, which is why they worked so hard to get it right - I belive 4.06 is the answer to everyone's problems!
And, when all else fails, as long as you have an older copy of Hoster still on your computer
that worked for you, as a last resort you can also use
Window System Restore, while you're waiting on new registration codes.