Markup Area Too Large

[sthguard]

Hi folks,

I'm tracking changes in a document I'm editing, but when I opened it this evening the gray "Markup Area Highlight" section had tripled in width, so I have to scroll over a full screen to see the end of the comment balloons and other tracked changes (see attached partial screenshot). This really cuts down on the screen real estate available for the actual document, making it much harder to read and edit. I've tried adjusting every option I can find, and so far the problem only shows up in this document-- new documents are fine, and documents with previously tracked changes are also fine. Any ideas on what might be wrong?

Thanks in advance.