A family of Microsoft word processing software products for creating web, email, and print documents.
Despite what the Navigation pane's right-click menu shows, the pane doesn't work off of heading styles only. If the corruption changed the definition of one or more non-Heading styles to have an outline level other than Body Text, then paragraphs that have that style applied to them will also appear in the Nav pane.
To check this out, display the Styles pane (Ctrl+Alt+Shift+S). Select one of the paragraphs that shows up in the Nav pane in error, and locate that paragraph's style in the Style pane. Hover over its name, and its definition will be shown in the tooltip. If it shows an outline level like "Level 3" (or some other number), right-click the style's name and click Modify. In the Modify Style dialog, click the Format button at the bottom and choose Paragraph. In the next dialog, set the outline level to Body Text. You might have to do this to several styles to wipe out the problem.