eth0: NULL pointer encountered in RX ring, skipping

[Andrea Ferraris]

After such kernel message the network interface (kernel 2.4.2) replied to 
ping from other network's machines with times varying between 200 and 2000 ms
and it was almost impossible to use the network to transferring files to or 
from this PC.
The card is a SIS960 on the mboard on an Acer PC with a Celeron 666 Mhz 
processor.

The problem was solved with a shutdown -h, powering down and powering up
the PC.

Can somebody explain the trouble?

Best regards to all all and thx to replying people,

Andrea