It looks like the size of the subform/datasheet control is too large.
Does it need to be that big? - if not decrease it's height until the
problem disappears, or alternatively turn on the vertical scroll bar in
the form so you can move up to the top.
Thanks for the tip. As it turns out, I had too much main form below the
subform/datasheet. When I brought the bottom of the form up, everything
turned out fine. Thanks for pointing me in the right direction.