In order to stop SharePoint from asking for credentials when the site is loaded or a document is accessed it is necessary to alter the security settings in Internet Explorer.

N.B.  This requires that Windows be set to remember your password and it should only be used in a secure environment.

With that in mind the steps are as follows:

1.     Open up internet explorer and browse to the SharePoint site.

2.     Enter your username and password and select 'Remember my password'

3.     Press 'OK'

4.     You should now have the SharePoint index page.

5.     Go to 'Tools > Options'

6.     Click on the 'Security' tab.

7.     Click on 'Local Intranet'

8.     Click the 'Sites' button.

9.     Under 'Add this website to the zone:' the address of the SharePoint server should already be filled in.

10.   Untick 'Require server verification...' and click 'Add'

11.   The address should move down to the box under 'Websites:', click 'Close'

You should now no longer be prompted to enter your credentials when accessing the SharePoint site or editing documents.