It sounds like you are saying that when InfoPath opens your form, there is enough whitespace that there are scroll bars showing on the side of the application itself, is that correct?
A few things could be causing that. There may be whitespace characters below your controls (i.e., the Enter key was pressed repeatedly). There may be a layout table that is set to a wide row width.
You can always try creating a new view, and copying your form controls from the "bad" view into the new view and then preview to see if that fixes it. If you want, post your template with a reply (under the Options tab) and I can take a quick look at it.