[Dovecot] Authentication Failure

[Dovecot]

I installed Dovecot on our FC3 sendmail server and get this from our Dallas office ( out of state to me ). 

dovecot(pam_unix)[13823]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost 

Only one Dallas user can get mail (pop3 or imap). All local users work fine. 
I ended upgoing back to UW and all works fine. 
What should I look for? 

Thanks 
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