Error:Microsoft Outlook 2007 keeps Asking For A Username And Password

Fix: When using Outlook 2007 you receive a prompt that is asking for a username and password.

Usually the prompt box text says

This issue is related to Exchange CAS server IIS SSL settings.

Note: This fix apply to Microsoft Exchange 2007 and 2010

The fix:

To fix this problem we need to change the SSL settings to accept the user certificate.

To change the IIS SSL settings follow the steps below:

Open IIS Manager -> Sites -> Autodiscover virtual directory

In the right panel select SSL Settings

Change Client certificate from Ignore to Accept