It seems when I first setup a new user in Outlook 2007, a login prompt comes up and asks for credentials. After the account is setup, the login prompt will repeatedly prompt throughout the day and is a little annoying. This happened recently as all other machines are not doing this - just a few machines on the network (The new HP 8200 Elite small form factor machines to be exact) Outlook 2007 works perfect on the other HP models we have - HP 6000, Optiplex 330, Opti 320's. A few of the HP 8200's work and the new HP 8200's give us the prompt. Any help would be much appreciated.
have seen this issue in the past. This article helped me.
I've seen this happen on Outlook 2003 with exchange 2010. Not certain it's the same as your problem, but the symptoms are the same.
My fix on windows 7 clients was to go to Control Panel -> Credential manager, and add a windows credential for the address of the mail server. Include the domain in the username field.
That resolved the password prompts. It also works on XP clients, but it's under manage network passwords in the users section of the control panel.