>I built a form in form designer.
>Contains a pageframe. On page 1 I have a combobox with
>a list of vendors. In the valid clause on the cbo I
>populate an array property of a listbox on page2, then use
>...activepage=2. Page2 is displayed, but the cbo from page1
>is also showing!!!
>If I use the pageframe tabs to toggle to page1 and back
>the control goes away. I'm sure the problem is related to
>switching activepage within a control method, but that seems
>a perfectly reasonable thing to do...???..

Yes, for some reason it may happen (valid event is not very good). You may add timer to your form with code in its timer event to change pages. Make this timer disabled normally, and enable it from the valid event.
PS: timer event code should disable itself at the end.