MS Word 2002: double space erases pages

In MS Word 2002 running on Windows XP I have found that when I try to double-space a document, pages disappear, e.g., a 39-page single-spaced document becomes a 51-page document, and certain pages are gone.

I have uninstalled Office, reinstalled, and still have the same problem.

I am also having random compatibility issues with other, non-Office applications.