Solved: Cisco Router vs. Internal DNS Server

After our old plastic router died, I replaced it with a Cisco 2821. Now I have only one problem with this. We have an internal DNS server, and when the Cisco 2821 is acting as our gateway with the internal DNS server, the DNS resolutions are either EXTREMELY slow, or do not work at all. However when the Cisco router is configured to use a public DNS server in this case I used Google's 8.8.8.8 . Everything works fine and DNS resolutions are fast, but none of the internal server host names can be resolved. The old plastic Cisco RVS4000 used to work fine with the Internal DNS. I can post the router's running-configs for both setups if necessary. Is there anything I'm missing, like opening a port for the internal DNS server? Pinging Internet IP addresses works fine, and even a speed test shows our full internet speed. I can supply any more needed information.

Thanks!

-Austin


EDIT- The Internal DNS Server is a Windows Server 2008 R2 Machine