Question : TCP/IP stack bad on SBS 2003 box?

I noticed the other day that our remote offices were having trouble pinging our SBS box at our primary location.  Initially, the primary offices were able to successfully ping SBS box but as of this morning, that is no longer the case either by the ip or the fqdn.  

I can still access our SBS server from the START, Run command and by terminal services.  I can also ping all the other servers and clients FROM the SBS box but they cannot recognize that box is even on the network.  Ive tried disabling the AV firewall on our SBS server, restarting the dns service and eventually the server itself.  Ive also confirmed all the ptr and a records in addition to the NIC configuration.   Ive run dcdiag and netdiag /fix with no luck.  I also ran dcdiag /v /test:dns.   This last test reveals a number of forwarding errors but comparing the configuration with one of our other servers didnt show any differences.  

Per this article, http://support.microsoft.com/kb/317518/, I suspect that I may need to reset the tcp stack on the SBS box but as this is obviously the primary DC, Im hesitant to do so.  Any other ideas on what might be causing the behavior I described?
 
For further information, we are running 7 servers, all server 2003 except for the one SBS 2003 box.  We have two servers acting as secondary dc's and the SBS box as the primary.  

The only hint towards a possible cause, is an error I show in the dcdiag /test:dns call following after every FQDN listed in the Root Hints tab of the DNS server tab :  

      DNS server: 193.0.14.129 (k.root-servers.net.)
      1 test failure on this DNS server
      This is not a valid DNS server. PTR record query for the 1.0.0.127.in-addr.arpa. failed on the DNS server 193.0.14.129  [Error details: 9003 (Type: Win32  Description: DNS name does not exist.)]

The odd thing is that these are the same listings on our other servers which are working just fine.  

Answer : TCP/IP stack bad on SBS 2003 box?

Make sure that all of your machines point to one of your own internal DNS server - The SBS box as the preferred DNS server and if you have other internal DNS servers you can put these as alternate DNS servers - otherwise ithe alternate should be blank.

I would always use a forwarder rather than relying on root hints - pointing DNS forwarders at your ISPs DNS servers is more efficient.