I have vpn setup like this.

172.16.1.0  -- M0n0wall <-------> 3com VPN -- 172.16.2.0

It works and I can access things ok, but once in awhile something wierd happens and I see in the
firewall log a block happened.  The firewall is blocking access to the 2.0 side for some reason. 
Example:

X  13:48:24.392140 LAN 172.16.1.18, port 1253 172.16.2.239, port 9600 TCP 

I even created rules on the LAN side in the Firewall with 172.16.1.0 to 172.16.2.0 to allow all type
tcp,udp, etc and all ports.   It still pops this up.  And the block still occurs.

Am I missing something?  Why would m0n0wall block traffic going across the vpn?

Thanks
Matthew