v2004 didn't use HTML for custom items. The old method used to allow you try write custom executable files (exes) that could be run and could communicate with MediaLab re data and such. HTML and HTML forms turned out to be a vastly more intuitive way to develop custom items. So, this means if you run a custom item that was generated with HTML (e.g., for v2006 and later) then it is probably not going to work in v2004. Why did you have to downgrade to v2004? Just curious.