[Zope] WebDav and Office 2000

I'm having trouble getting Office applications to work with the webDAV interface to Zope. I have Zope (running on Debian Woody) serving rendered pages on 9673 and source on 9674. I can save Word documents to folders on Zope (usually) but if I try to open them again I get a read-only document containing the single line "downloading from http://zope.etc.etc". This happens regardless of whether I point the web folder at port 9673 or 9674. Any clue to what I am doing wrong? I don't have any problems accessing source and rendered documents using cadaver, so is this a simple Word/Office/Win2k incompatibility? -- Bruce