A family of Microsoft word processing software products for creating web, email, and print documents.
If you are saying that deleting one paragraph mark deletes all numbered paragraphs, then your document must certainly be corrupt.
Losing a paragraph number for a single numbered paragraph can be fixed with Ctrl+Q, assuming that numbering has been correctly defined with a paragraph styles attached to each numbering level. See http://shaunakelly.com/word/numbering/numbering20072010.html for assistance.
Note that there isn't a general problem with copying styles through the Organizer; the problem I was referring to is with copying numbered styles, and it is well-documented, especially in the old Microsoft newsgroups. Of course, chances are that the bug has been fixed so that copying numbered styles now works flawlessly. If so, that is great.