dual core, dhcp client stops

My platform is a dual-core Xeon machine which is similar in many respects to
a single core Pentium-M machine that has hosted our application for a couple
of years. Except for a few HW components, the TD configuration is very
similar however the DHCP client and Win32 Time Service on the dual-core
machine are stopping with exit code 1747 (RPC_S_UNKNOWN_AUTHN_SERVICE)
immediately after boot. All dependencies are satisfied and the fbalog from
both machines looks just about the same. The configuration is fairly
light-weight with minlogon and command shell. There was no problem running
XP desktop on the dual core machine. Any ideas how I can prevent the DHCP
client in particular from dying?

Luke