Mailbox password change problem

[vexcor]

Hello we updated our servers to 3.0.4.5 and we have problem with edit mailbox user. Password change doesnt work. We are changing in standard way via admin and mailbox edit form. After submit form with new password interface said save, but any changes. Password still old one. Any other changes as forwarder, mail copy, autorespond etc. work without problem, only change password doesnt work.
We have setup with two servers:
Server 1: www, dns, mysql
Server 2: mail, dns
I tried find some errors in logs but nothings on both servers. I tried mysql permissons too, but all settings is good without errors.
Where can be problem? We need fix it, its very big problem!