When reading a PDF, I go to click on a word to highlight it and that works. But sometimes, once that is done (and sometimes just randomly), somewhere else on the page acrobat begins to highlight in black one word after another, (you can still read the word in white underneath) as if it were reading to me (but the read aloud function is disabled) and I can't stop it. The black highlighting is only for a split second and then moves onto the next word to highlight it. As it highlights it moves the page across and up and down. It is really distracting to the eye and I can't read properly. How do I stop it? Please help!!