DNS multiple entries for server

I have a windows 2003 server running as my domain controller and DNS.  My network is behind a Cisco PIX and I have VPN enabled.  The Pix passes through any VPN traffic and lets windows handle it.  The issue is that in the DNS forward lookup zone I have two entries for my server, one is the correct IP the other is an ip in the correct subnet but doesn't correspond to anything.  I checked the DHCP leases and found out that there is a block of IP addresses set aside for VPN users.  The IP that is showing in the DNS is the last IP in that block of addresses.  The entry shows up as a host(A) entry and it also shows up under the properties as one of the IPs for the name server.  I have tried deleting the entry from both locations but as soon as I reload it comes back.  This is causing an issue for several users since when they try loading up outlook for example it may take a while because its looking for the wrong IP.  On the client machines if this occurs I can do an ipconfig flushdns and that usually fixes the problem.  

Any help would be appriciated.    
Thank you