Sure thing.
1) Open your form in design view (so that you can edit it).
2) The form properties ("Property Sheet") should be on the right side of the screen.
3) Select the Event tab.
4) On Current is the first listing. On the dropdown, choose [Event Procedure]. Then, click the elipsis (...). It should take you to the VBA editor.
5) Under Private Sub Form_Current(), you put something like this...
-
If Me.CHECKBOX-NAME = True Then
Me.TXTBOX-NAME = Disabled (I'm not sure how your disabling it)
ElseMe.TXTBOX-NAME = Enabled
End If -
Hope that helps a little.