Outlook 2007 Continuously Prompting for POP3 Credentials

Recently, I had a customer running Outlook 2007 on Windows 7 that experienced a condition I like to refer to as "the dreaded attack of the authentication dialog box." She was connecting to a POP3 server and had the "Save password" box checked, but during every Send/Receive session, would get prompted twice for credentials.

The solution was simple, but elusive.

1. Close Outlook.
2. Open Windows Explorer.
3. Tools > Folder Options > View; click "Show hidden files, folders, and drives."
4. Deselect "Hid protected operating system files (Recommended)" and click OK.
5. Navigate to %USERPROFILE%\AppData\Roaming\Microsoft\Protect.
6. Rename the folder S-1-5-21- to S-1-5-21--old.
7. Rename the file CREDHIST to CREDHIST-old.
8. Restart.
9. Launch Outlook, enter credentials when prompted, and click Save Password.