Is it possible that you had an earlier version installed on a different drive than the one you are installing this version on? If so I had to go to the original drive it was installed on and find User/Your Name/App Data/Local/DVDFab and delete the folder and than install and click on the key for version 5.

Probably an easier way (in Vista) would be to uninsall DVDFab from the Control panel, Restart, click on Start Icon, search for DVDFab and delete the folder that is found.

Reinstall DVDfab, Double click the version 5 key and hopefully this will solve all your problems. The one gotcha is after the program restarts the screen telling you that you have a trail version may still be visible, just close it and you should not see it again.

I cannot guarantee this all will work for you, but it has worked for several friends.