The system I have hooked up to a CRT via S-Video has the following...
EP-8KDA3+ NVIDIA nForce3-250 Socket 754 with audio, SATA, 1GbE LAN
NVIDIA Boot Agent 201.0440
Nvidia 6200 PCI video card.
At this time the system has spawned twice.
Once with MAC address 00:04:61:FF:DF:FF:FF
Second with MAC address 00:04:61:FF:FF:FF:FF
There is a single on board NIC.
This is obviously related to forcedeth drivers.
Just to get this system to even PXE boot without failing has been interesting.
At the moment I'm just trying to work out a routine that provides consistent MAC assignment.
Prior to using this system Windows 2000 told me the address was FF's.
The BIOS reports the address as DF.
Sometimes it boots one way, sometimes the other.
At one time it wouldn't boot if the AC97 audio out to the TV was connected.
I've seen similar. It seems to be related to nvidia based nics. The solution is simple though.
Disable one of the nics in the BIOS. That fixed it for me, on 2 systems.
BTW, you can thank Zaerc for that one, he taught me that at linuxTAG last year