MDaemon: Error writing to winsock

Hi all,

I'm having a problem with my MDaemon Server (v8.1.5 - latest available).  Whever a connection is tried via SMTP it reports back:

Mon 2006-03-20 13:03:27: Session 11; child 1; thread 260
Mon 2006-03-20 13:03:27: Accepting SMTP connection from [x.x.x.x : 53358]
Mon 2006-03-20 13:03:27: Error writing to socket
Mon 2006-03-20 13:03:27: Winsock Error 10054 Connection was reset by the other side!
Mon 2006-03-20 13:03:27: SMTP session terminated (Bytes in/out: 0/0)
Mon 2006-03-20 13:03:27: ----------

And that's all.  Any suggestions as to what could be causing this?  It's installed onto a Windows NT server.  Which leaves me with another option.  I've installed it on my Windows 2005 server and instructed the route to route all SMTP requests to the new server and that just blocks it completly, no message at all in MDaemon.  I assume this is something Windows 2003 is doing to block the port, but I've disabled the Firewall on that server to be sure, but no change.  Would love to get one running.

Many thanks

Lee