Word 2010 Multilevel list - Numbers disappear

This is how my woes started! The first time my numbers went poof, it was after I had PDFed my doc. Keeps happening, with closing/reopening, saving, printing, etc. - not every time, but every now and then. 

The fix (for me) has been simple, if obnoxious since I keep having to do it whenever the numbers break: 

1. Click somewhere that should have a number and doesn't
2. Click the Multilevel List dropdown
3. Right-click on the List Style in use and click on Modify from the right-click menu
4. Click the Format button (lower left)
5. Click Numbering
6. Click Okay in the Modify Multilevel list window that appears, then again in the Modify Style window

Numbering fixed.

Not sure if it will work for you, but the whole process takes about 10 seconds whenever my numbers break. So irritating, like swatting a mosquito, but it fixes it. I usually save again, close and re-open whenever this happens to make sure, and in all my docs, I save, close and reopen before sending them out.

Automatically Update is switched off in all our templates - we produce and share a vast number of documents with third parties under very tight time scales.  Therefore all the "helpful" options in Word are either neutered by Group Policy or Template design.

This issue has to be a bug.

We have worked with the same numbering system and broad spectrum of templates for 10+ years, mainly in Word 2000.

Only after upgrading to Word 2007 we've seen this issue - IIRC the multilevel numbering systems/ logic where updated within Word with Office 2007?

So here's the *sigh* IT is tiring bit.  The problem only appears in some documents edited in a particular manner...

The user has to remove numbering from a numbered clause (using a numbered heading style) using [BACKSPACE] to remove the numbers instead of applying a non-numbered heading style.  At this point the document may or may not corrupt...if it does the user will reopen the document and all or some of the numbered heading styles will lose their numbering - it simply evaporates...

Copying the content only to a fresh template and reapplying the heading styles involved fixes the problem.  Attempting to repair with the document or the styles "in situ" has no effect.

That to me suggests that Word 2007 has corrupted the heading styles involved within the original document.  I suspect that Word is trying to update the styles (but not all the time) and this causes the error - even though automatic updates are disabled.

It's not the end of the world - but it took me months of head scratching to come up with this suggestion. 

Remember we do not permit any of our templates or documents to apply automatic updates.

Thanks Stefan:

I went back and restarted the list as you recommended.  This did eliminate the problem of having to manually set the number at various places (once I removed the traces of the old settings). Once I got the numbering fixed I went back in to outline mode and set the levels.  Everything looked great...so I saved the file and closed it. When I reopened the file all the numbering was gone.  The styles remain and the assigned levels remain but no numbers remain anywhere in the document.

I did define a multilevel list and associated each level to a style (set by my client in this case).

I am at a loss again....

Thanks for the response! Automatically update document styles is not checked (and wasn't before, so shouldn't be the problem - I did check it, though!)

My document is already set up with multilevel lists, with heading styles linked to each level of the list. The styles I am using are Headings 1-9 that I have formatted. They are numbered via Multilevel lists. As I'm thinking about it, though - the heading styles may also have numbers set within them (in addition to the Multilevel list settings) - maybe that is causing a problem?

Best to set up the numbering in the template rather than a document.  Then the styles\numbering scheme will be available to all documents created from the template.