Form Layout

I have a main form that contains 3 tabbed sub forms. The sub forms present as datasheets.



When I select the second or third tab the main form scrolls up a row - and I don't want this. Naturally when the user flicks from one tab to another they would want the main form to stay in the same position and not change its presentation.

What aspect of the format of those sub forms would scroll the main form?



thanks

Form Layout