Word – How to open the Document Map in Microsoft Word

There's a problematic section in your Word file that’s causing this.

The part of your document with the most errors in the Document Map, is the one. Extract this to another file. Then copy & paste the remaining contents to a new document and it should be clean. :)

Yes, don't use tables. For one thing, the headings won't show in the navigation pane (if that's important to you). The page that DavidPostill linked to gives the basic info, but if you're using a recent version of Word, some of the information about frames on that page is a bit dated. You don't need to use the Developer tab to insert a frame. That page also doesn't explain how to add the vertical line down the left side of the body text.

1. On the Layout tab, set a wide margin for the document.
2. Click in the header (or footer) area to open it for editing.
3. On the Insert tab, insert a Word shape. Select Line as the shape, and draw it in. Don't worry about getting the length and position right. You'll adjust those next.
4. On the Format tab for the shape, on the Size tab, set the height to Relative, 100% relative to Margin. On the Position tab, set the horizontal position as desired, so that the line will appear to the left of the body text. Set the vertical position to Alignment, Top, relative to Margin. Select the Lock anchor check box.
5. On the Home tab, in the list of styles, right-click whichever heading you want to be a side heading, and then click Modify. In the Format drop-down, select Frame. Make sure that the text wrapping is set to Around. Decide how wide you want the side heading to be, and enter that as an Exact width value. (For example, if my left page margin is 150 pt, perhaps I want the side headings to 90 pt wide, so that there's space between the heading and text – with the vertical line that I added in between – and also space between the heading and the left edge of the page.) Set a horizontal position. You'll likely set it as some absolute value relative to Page. Depending on the heading's font and paragraph settings, you might have to tinker with the vertical position to get everything to line up correctly.
6. Type your document text as normal: Heading paragraphs followed by text paragraphs.