So here is the situation
I'm replacing a netgear prosafe or something at the head office with a Cisco 1800. I had a few VPN tunnels coming into it connected to other offices/vendors and the tunnels worked fine.. In my main office I have a Domain controller that is the main DNS Server for our internal network. It also our external Facing DNS Server as well ( I know I know) I just inherited it.. So everything works fine with the netgear. When I configure the 1800 and get it working, the tunnels come up and everything is good, except for one thing.. I have an office with an XP Machine and a small netgear router with a vpn tunnel to the main office where the DNS Points to 10.51.44.9 which is the IP of the DC. Once the Cisco was put in it could not query that DNS server at all. I have the nat statement..
ip nat inside source static udp 10.51.44.9 53 interface FastEthernet0/0 53 in the 1800 to allow for outside access to this DNS Server. When I take it out. DNS works fine again on the XP Machine.. the problem is I can't leave it out or everything will stop working..