Entire document momentarily flickers white when editing/adding text

Using Adobe Illustrator I exported an Adobe PDF.    Back in Adobe Acrobat Pro -> content Editing ->   I select some existing text and  as soon as I type a single character, the entire document momentarily flickers white.   Afterwards, the character I entered is visible.   This happens each and every time I try to type.   If I try to type a full sense, the screen is basically strobing until I stop typing.

This also happens in Acrobat Acrobat Professional.

I have Acrobat Pro 11.0.06

thanks!