When orientation changes from portrait to landscape, the acroforms are not in the correct position. It almost seems like the actual pdf document is larger that what the viewer shows. This can be told because when I try to highlight the pdf text, its also not aligned with the viewer. Its kinda like the viewer is showing a scaled version of the document, but the document graphics and acroforms do not truly conform to the scale.
The mispositioned acroforms can be put back in the right place if the viewer is put back in portrait orientation and fully zoomed out.