I think it's a bug in VFP9. We have seen the same behavior and there were some threads indicating it. How complicated is your form? Can you create a test case out of it and send to Microsoft?

Related threads:
Re: Listboxes bug in VFP9 Thread #1042967 Message #1043099
Re: Listboxes Pageframes & VFP9 ? Thread #1036285 Message #1036419
>Hi All,
>
>I have a ListBox on a page of a PageFrame. When the form loads the items in the ListBox are unavailable. I mean, it doesn't look like anything's wrong but I can't click on them or select them or nothing. However, after I click around on some other Pages ListBox controls, all of a sudden they all work. I don't think this is something new. Does anyone have a solution?
>
>Aloha,
>
>James