[Exim] Problems with exim running on port 25 / Debian

Been using exim on Debian for around a year - with the standard 3.3x
dist for the stable release without a problem

Recently updated it via apt-get from a security release and started to
experience problems.

The internal routing on the machine is fine ... But anything coming in
externally over port 25 gets the heave ho


Any ideas? I've had to resort to a lousy windows MTA I get it fixed.

A telnet to it establishes a connection and drops it immediately

Trying 192.168.0.3...
Connected to 192.168.0.3.
Escape character is '^]'.
Exim is a Mail Transfer Agent. It is normally called by Mail User
Agents,
not directly from a shell command line. Options and/or arguments control
what it does when called. For a list of options, see the Exim
documentation.
Connection closed by foreign host.