Network Connections blocked

We have an office of 7 computers running various Windows
OS. Yesterday the 98 and ME systems lost thir connection
to the internet. It turned out that something had taken
over in the internet connections and hard coded an IP
address and a DHCP server address in the registry. It
could not be manually re-written or deleted. If I did so
it just came back on the next boot. It was as if
something was over riding the TCP/IP settings. To get
around it I had to set each connection with a static IP.

Today my XP systems experienced the same problem. I can
no longer use DHCP in the office. I have seen a few
other comments to this regard on other forums and a few
of my friends are experiencing the same problem. No one
seems to have a solution. Is this a new virus going
around?