DNS Error 5504

So this is wierd --

Checking out errors in the Event Log of one of our client's servers, and it has a lot of those notorious DNS 5504 errors. I know how to troubleshoot them when the IP address belongs to an ISP or other server, but the wierd thing here is that this particular server is using its own IP address for DNS forwarding (no other IP addresses listed). So how could it get an invalid domain name from itself? Is it even plausible to use a server's own IP address for DNS forwarding?

For those unfamiliar with 5504 errors, here is the actual description:

"The DNS server encountered an invalid domain name in a packet from x.x.x.x The packet is rejected. "

I've seen these from time to time but since there is no indication of there being any functionality being affected and no other indication of things being "funny" I put it down to a bad packet or similar screw up...

Are you having any other issues that might be DNS related?

Not really -- Other AD related things, but not DNS per se. However, I'm getting those bad packet messages every few minutes in Event Viewer, so it's a very repetitive error.

Make sure you don't have a typo in the zones on your server.

AD problems could be related to DNS errors. Meaning an AD domain controller can't find it's partners.