[Zope] [HELP] Zope & WebDAV problem

Hello, I have a problem using Zope 2.4.4 b1, Webdav and Offfice 2000. In fact, a can browse my site via WEBDAV, no problem. But, when i open a document (by double-click), a MS Word document for example, it's openned in Read-only mode. So, i can't save my modifications. I saw that this problem should be solved since Zope 2.4.4 b1. Can anyone help me ? Thanks in advance Frederic. PS : Excuse my english.