Our company keeps running into an issue with Kerberos/encryption settings within Outlook 2010 in conjunction with Microsoft Exchange Server 2010. When accessing user level Outlook Account Settings > More Settings > Security tab and setting the encryption to remain selected on "Kerberos" instead of "Negotiate authentication" we are finding that user's settings are often defaulting to "Negotiate authentication" again. Time and time again I am resetting these changes so a user will have access to their email again. This means I spend about 30% of every week resetting Outlook mail account settings for users just so they gain access to their email again/receive and can send current emails.

Settings on the Security tab:

Encryption (selected):
x Encrypt data between Micorosoft Outlook and Microsoft Exchange

User Identification (deselected):
o Always prompt for logon credentials

Logon network security (set to):
> Kerberos password authentication

This is not a password issue (either). All users are set to not allow their network passwords to expire when their original username and password are created.