Zooming in on a document causes broken scrolling

Greetings,

I have a client that currently uses Adobe Acrobat Pro XI. When he attempts to read a document, some of the time it will not scroll properly, especially if he is zoomed into a document. What happens is that the same page appears, but you can see that it is scrolling on the very, very bottom of the document (about 100 pixels in height). Once it scrolls to another page entirely, the new page shows, but it won't scroll properly until the next page. I've never seen this behavior before. I've attempted a repair install to no avail.

Has anyone else seen this before? Any suggestions would be appreciated. It's also important to note that this appears to happen on Adobe Acrobat Reader as well.