DNS Address Wrong In DHCP Scope

I have a Windows 2003 server running DHCP to several clients runing mostly XP Pro. Many of the clients intermittently pull a DNS address of 192.168.1.1 in their scope when the address they should receive is 10.0.0.1. When the faulty address is pulled applications such as exchange e-mail and many things runing from the server at 10.0.0.1 hang and won’t launch.

IPCONFIG/RENEW from the DOS prompt renews the lease coeerctly every time. Does anyone have an idea as to the source and cause of the faulty DNS address within the scope?