[kkielhofner]

This.

As I say in my updated post, this is a complex issue with clear combinatorial factors. More than likely it's not limited to one chip, one packet, or one EEPROM configuration. A quick reading of the web shows various unexplained issues with this family of Intel ethernet controllers randomly exhibiting the exact behavior I've described. Different controllers, different mobo OEMs, different EEPROM settings. Are all of these issues related to some kind of "packet of death"? Certainly not. However, are at least some of them? Almost certainly, even if they're not vulnerable to my (extremely specific) "packet of death". We still don't know exactly why this is happening (even in my extremely specific case).

[GiHe]

I have another interesting (and reproducible) manifestation on Supermicro motherboards with two 82574L controllers. In this case, it is again true that we only experience problems on the first (as ordered by ascending MAC address) of the two interfaces.

That was the case, though I did not clearly state so above, on the Intel motherboard with one 82574L and one 82579LM.