[otrs] Mail download stopped due to Can't create PID PostMasterMailbox Error

Hi, For some reason mails have stopped downloading in our OTRS 2.4.6 installation and we are seeing rows upon rows of similar error messages in System Log: Need User or UserID! Need TicketNumber! No article found for TicketID 567512! Can't create PID PostMasterMailbox, because it's already running (dev-crm.internal.directi.com/16490)! Upon researching this a bit, I ran across the following links: http://lists.otrs.org/pipermail/otrs/2009-August/028048.html http://lists.otrs.org/pipermail/otrs/2009-August/028052.html But the above URLs don't present a solution to this issue. Can someone help us to resolve this? Regards, Saurabh Pande.