We have 3 servers for mail service which are LDAP, MTA and Mailbox, 4 days ago we moved the mailbox to another server and we needed more space, the migration was OK, but we are experiencing problems with some users can not authenticate via POP port 995 and 110, we have to restart the service to be resolved in the log only find the following errors and warning in Mailbox.log

Mailbox.log :2011-12-19 02:08:27,559 ERROR [LmtpServer-2430] [name = lizlugo@pp.com, mid = 742; ip =;] jsieve - Evaluation failed. Reason: null
12/19/2011 00:01:46,423 INFO [Pop3Server-6000] [ip =;] pop --ERR Mechanism not specified (AUTH)

I would appreciate any suggestions.