For some reason MS Word 2003 likes to make my headers disappear. To make them reappear, I’ve been selecting View > Header / Footer. Saving the document template after making this change does not retain the changes. Finally, I found the solution here. It instructs you to click Tools > Options and select the View tab. Put a check mark in “White space between pages (Print view only).”
After you make the change, save your Document Template.