I have a client using Outlook 2007 on Windows XP SP 3. The OS is up to date. He subscribes to the paid version of Yahoo Mail and is configured to use POP3. The program will consistently ask for credentials and fails to authenticate to the server, no matter what attempts I make to resolve the issue. I have checked the credentials by logging into Yahoo Mail using the web interface. They are correct. I have checked "remember password". I have UNchecked "remember password". I have checked and double-checked the account settings. I have performed a "repair" from within Outlook. I have checked permissions in the Protected Storage System Provider registry subkey. I have removed Outlook 2007 entirely and reinstalled it. Has anyone experienced this issue, and if so, can you make any suggestions for a resolution? Thank you.