During startup syslog-ng queries the hostname using gethostname. Can you strace syslog-ng and look for this call to see what it returns?
We are also resolving this using the dns which is also interesting.
Thanks
OK - after much poking around (including testing this on a different host with this morning's latest source) here's what I found
I believe that syslog-ng is (for some reason) unable to come up with a correct hostname for the local system.
I would really like to know why this is happening