Need help with this one, we have an exchange server that has been operating fine for months. Today all non-admin rights users were unable to connect to their exchange accounts as they had to 'reauthenticate their credentials' The event logs show no major changes occured and we did not make any major configuration changes. What should we check? The users with admin rights can still log in and connect to their exchange account. We have other exchange servers and they are not behaving like this. There was no group policy changes made. Any thoughts, recommendations? Need help!

Any updates applied (sp2)?

Thanks for the reply, sp2 is loaded though. The issue is fixed, turns out the security logs weren't set to overwrite so they essentially got full. (That is how the admin rights users could still access their account while non-admin level users were getting the credentials could not be verified message) Thanks for the reply!

Wild, I wouldn't have guessed. Good work!