I am accessing the built in SharePoint 2010 on SBS2011 via Microsoft Office Excel and Word (opening a file from WebDAV http file mapped drive in Explorer).
When saving a file, I get prompted from within Microsoft Office 2010 Word/Excel for credentials - entering the correct credentials just prompts the window again.
Clicking cancel allows me to go to My computer -> mapped drive and save the file.
I am able to browse the SharePoint site via Internet Explorer without an issue and I am not prompted for a password when doing so, I presume this means Windows authentication is working via the SharePoint URL being in the intranet list.
I have also check that the sharepoint url is in the trusted intranet sites list.
Anything else I should look in to?
Have you tried using the following registry value? This usually works with integrated authentication (not basic/forms authentication).
Refer to the following document for more information:
Prompt for Credentials When Accessing FQDN Sites
http://support.microsoft.com/kb/943280
Here's something to try.
http://blogs.microsoft.co.il/blogs/choroshin/archive/2012/11/06/sharepoint-getting-authentication-login-prompt-when-trying-to-open-office-document-with-unique-permissions.aspx
There are 3 possible ways to solve this issue:
1. Add read only permission in the root of the site collection.
2. Deactivate the feature “ViewFormPagesLockDown”:
3. Run the following script on your site collection, this will add permission level to the “Limited Access” Permission level that you have in that site collection.