Text is Replaced Temporarily when Highlighting Text

For some reason, whenever I highlight text, Acrobat temporarily blocks out the text I'm working on and covers it up with other (seemingly random) text.  The random text dissapears as soon as I'm finished highlighting, but it makes it difficult to highlight multiple lines because the size of the cover text is much larger than the base text.  

I've ran the repair tool and the OCR tool with no success.  This also happens on pretty much every document I have. I know this is confusing so I included a few screenshots. The first image is without any attempt at highlighting. The second shows what my text looks like after I attempt highlighting. 

Any help would be appreciated!