You need to iterate backwards because formcount changes as you release forms. Try

for i = _screen.formcount to 1 step -1
etc.

>I'm trying to release all forms, other than the main form, when a button is clicked. They are not in a form set. The code works fine when the main form and one other form are open, but once I open more forms the code fails with a "FORMS is not an object error."
>
>For i=1 to _screen.formcount
> If _screen.forms(i).name<>"frmMain"
> _Screen.forms(i).release
> Endif
>Endfor