SonicWall TZ-170 DNS, Exchange questions...

I recently installed an exchange (2003) server on our network.
I have a Win2k AD Domain & am having a few problems getting mail to & from
some users, but not all.
I recently turned off forwarding on my DNS server & let it use the root hint
servers, as I read that this can cause problems.
I also see alot of entries in my sonicwall log like this:
UDP packet from LAN dropped - 192.168.100.249, 53, LAN - 192.168.100.254,
3195, LAN - UDP Port: 3195
192.168.100.249 is my DNS Server & 192.168.100.254 is the SonicWall's
address. The UDP port changes, however.
I originally had port 53 open to & from a DNS server at my ISP.
Should I change or add anything?