svchost.exe consuming 99% of CPU

& network services not working

This just started in the last day or so. Nothing new installed on this PC.
I had just re-built the Win-2K Server and this Win-XP-Pro PC (in the same room) stopped receiving DNS results. I assumed at first the problem was in the Server, so I tore down and rebuilt DNS, DHCP & NAT with no success.
Tried from another PC – the Server is working fine.
The “broken” PC won’t even get DHCP info when directly connected to the ISP.
I also noticed that svchost.exe is running between 95% and 99%. If I kill that instance of svchost, no network services work – even dis/enabling interfaces.
Help!