Receiving wrong DNS address with DHCP HELP!

Okay, I've never seen this before. Twice since yesterday I've booted up a
computer (two different machines) only to find out I couldn't access the
Internet. Ipconfig showed the wrong DNS server address and the wrong
connection suffix but all of the other information was correct. The DNS
address started with 192.xxx and my network is 10.xx. I can't figure out how
this happened. Doing a release/renew solved the issue on each computer but
I'm concerned about where this came from.

My network is mixed mode NT4/2000/2003. The DHCP server is on the NT4 box.

My only thought is that somehow a user connected via VPN has a home router
responding to DHCP requests coming from my network through the tunnel. What
I can't figure out is why is on the DNS server address the one that's changed?

Any help would be appreciated.

Thanks,

Dave