Miroslav Kratochvil [off-list ref] :
[...]

Many users who have onboard Realtek 8168 network controllers in
combination with nVidia hardware (mostly nVidia graphic card and/or
nForce motherboard (MCP5x) ) experience still-not-very-explained
hangup triggered by heavy network usage which fills a tx buffer, and
(speculation) causes race condition on irq sharing, resulting in
absolute freeze (not oops/panic). On all affected machines I've seen
this fix solved the problem:

Where can the reports of these users be found ?

-- 
Ueimor