i believe i had mentioned this already on this list:
have had same problems with my asus m2npv-vm board (onboard forcedepth nic) the first days with the board under fedora 6 - would say no big diff's to centos-
the fedora way goes:
1. move or delete /etc/sysconfig/hwconf 2. move or delete /etc/modprobe.conf 3. run kudzu afterwards => this writes new hwconf, modprobe.conf 4. bring your nic's down: ifdown ethx 5. remove the driver via modprobe -rv <your-nic-driver> (forcedepth) 5a. maybe to be sure: lsmod|grep -i <your-nic-driver> 6. reload the driver via modprobe -sv ... 7. fix your mac-addr-settings via system-config-network 8. compare your mac's in hwconf _and_ via ifconfig
steps 4-6 are also performed via reboot (grrrrrrrrrr: m$ world tasks), but your are able to exclude if this files were changed again after step 3. (ls -l /etc/sysconfig/hwconf => date/time !) a hint of another problem !
if there are still diff's, then it's another problem i don't know a solution for, yet, but i remember ethx order changes and therefore mac mismatches at late fedora 5/early fedora 6 kernels.
try and report ! okay ?