It would be my guess that you inadvertently saved that partial document as your base Word template. In Word, that base template is called "Normal.dot"
(Note that I said .DOT, not .DOC.
A Word document ends in .DOC, a Word template ends in .DOT.)
If you ever mess up the Normal.dot, Word has a very easy, built-in method of fixing it.
All you need to do is delete the old one.
Don't do this with Word already running, to avoid some odd complications.
Also, if you want to cautiously approach this, instead of deleting the current Normal.dot, just rename it. Once you do the steps, that I'm about to tell, and everything works as expected, then just delete that renamed file.
Now, how do you find YOUR Normal.dot?
(Note: every user on your PC will have their own version of the Normal.dot, so we have to find yours.)
In all the latest versions of Windows (XP, 2000, ME, 98 and possible 95) the individual files for each user are in the C: (assuming you are setup with a default C: drive) and in a folder called "Documents and Settings"
Then, in a folder of your Windows logon name, and let's assume that you use "Eleanor" and then even further down the path through "Application Data" then Microsoft, and finally "Templates"
All spelled out, in one line, that would be:
C:\Documents and Settings\Eleanor\Application Data\Microsoft\Templates\Normal.dot
But you don't have to dig through all those folders to get there, let's just use the Windows Search (or Find) tool.
Hold down the Windows key
(the one with the Windows symbol on it - also now being called the "Start" key)
and press the F key.
That will open your Search window.
In the "All or part of the file name" field enter "Normal.dot" (not the quotes!) and click on the [Search] button.
After a few seconds, at least one hit will show up.
(Note, there may be more, there will be at least one for every other user on your PC who has used Word, and there might even be the remnants of other Normal.dot files with those characters in their name - like maybe a file name like "~$Normal.dot" but don't worry about those.
When you finally see the one that has the path that I mentioned above, just click on it and then right-click it.
Select the [Rename] command.
Just add "OLD" to the current name, so it will now be called "Normal.dotOLD"
(Note, I want you to just add to the end of the file name, so that, if needed, you can still find the renamed file later, using the same search detailed above.)
So, after renaming your "Normal.dot" and effectively not having it available for your Word program, just start up Word, and see if your problem still exists.
If the problem is fixed -- GREAT!
If not, then either you didn't follow my instructions, please check your work, or...
or else I don't know what the heck your problem is.
And I am sorry. Please just revert your file name back to what it was and I'll silently go away.