Well...I'm stumped. Personally, Id' try setting up another syslog
server to rule out any misconfiguration on the current syslog server.
http://www.kiwisyslog.com/ has a free syslog daemon that will run on
windows.

kiwi also has a syslog message generator testing the configuration of
a syslog server. Again, another free tool.

Sorry I couldn't have been more help.

-Don