While searching on the WayBack Machine I decided to go on www.dragonballz.com/ because why not? Clicking on Sep 25, 2004 I noticed in the left hand column it says "Live Action Movie". The only live action film I remember was Dragonball Evolution in 2009. It's seem's very very possible there may have been ceased production of a different live action Dragon ball Z movie out there.
I find that interesting as well. As a huge DBZ fan since it says "Live Action Movie" you can't really write it off as one of the other 19 movies. We should look into this. My idea is it was the beginning of preproduction on the Dragon ball Evolution Film since its not that far of from when your saying.
But if you go to 2004, more information in regards to contacts is discussed, with the consensus being reached that this movie was not/never was being made (confirmed from many sources in the post)-
I'm not really sure why this "official" website was posting about rumors, but at any rate it seems more like a big playground rumor that was being passed around in the community.
What would become Dragon Ball Evolution was in development hell for a number of years. It only got made because of the writer's strike, because Fox was desperate for releases so they dusted off an old script they had and put it into production.
This started all the way back in 2002, I believe. I remember that the site even had polls for who would play Goku and Vegeta (Jet Li and Jackie Chan respectively won), and for who they'd want to direct (George Lucas).