I faced this problem recently at a customer.
They had pure Windows XP with Office 2003 deployed to their clients. These clients were accessing a SharePoint 2003 site. When they started deploying new Windows 7 clients with Office 2007 they found that when the users clicked on links to Office files which they had read-only permissions to, they would get prompted to enter credentials. But entering credentials doesn’t work. If they hit cancel or escape, the prompt would disappear and the file would open as expected.
Being a good PFE, the first place I started was with Network Monitor traces. I was looking for any strange “access denied” messages, authentication attempts with mismatched methods, bad HTTP redirections, DNS problems, that sort of thing.
Here’s what I found:
So what is going on?
WebClient is trying to take a write lock on the file. But the file is read-only to the user, so this fails. We see 4 requests to GET the file, each one has a reply which says “unauthorized”:
Then I found this article:
This says that by setting the registry value UseWinINETCache = 1 you will instruct Office to always open web-based files as read-only. If you need to edit the file on a SharePoint site, these will be opened as read-only also, so this will fail. To work-around this limitation you must do one of the following when editing a file:
Note this limit applies to ALL web-based files opened by Office, even those on SharePoint 2007 and 2010, which do not experience this problem. Therefore, this is only a work-around until you are able to upgrade your SharePoint 2003 sites to 2007 or 2010. Note that Internet Explorer 8 is NOT a supported browser when accessing SharePoint 2003, for this reason and others.