[Pierre-Marie Baty]

99.9% certain it's a hardware issue. A badly written driver or a not-so-genuine chipset on your network card that screws the whole thing up. Some cards use common chipsets with known bus addresses but change the IRQ without notifying the BIOS, and as a result these cards most of the time fail to receive messages from the main bus (because they listen at the wrong time on it). Change your netcard, or try another kernel.