Well, i´m always facing this problem and its very bad for me to handle thousands of accounts with password sync problems. Everytime a user change the passsword from the Webmail, the password from samba its not sync. If i change by the administrator area, it sync. If i made a stop and start for zimbra, it works for a little time, then it fails again some time before.
When i restart the Zimbra (zmcontrol stop | start) this error appears:
I´m using the zimlet for samba posix/samba accounts, ZCS OpenSource 6.0.8 and Samba 3.5.4. INFO: I/O exception (java.net.ConnectException) caught when processing request: Connection refused
 INFO: Retrying request
ERROR: zclient.IO_ERROR (invoke Connection refused, server: localhost) (cause: java.net.ConnectException Connection refused)
If anyone can help me with this i will be so gratefull.