[Zope] WebDav Woes

Hi Folks I have a zope installation on an odd port (7070 for main requests, 7090 for webdav source) Anyway, I can do some uploads/downloads of objects in webdav, then after a while I get an error "An error occurred copying some or all files" when connecting with Windows Internet Explorer (open as web folder option) I suspect it has something to do with locking but restarting zope does nothing to correct the problem. Has anyone run into this before? -jim