Total newbie to linux and ubuntu but loving it.

I'm running Ubuntu 9.0.4 on a Powerbook G4 set up as an AFP file server through Netatalk 2.0.4. Most of the time it works like a charm, but occasionally it reboots spontaneously which is very, very bad.

Just before the reboot, the syslog shows hundreds of records like:

comp_name kernel: [some number] eth0: RX MAC fifo overflow smac[some number].

Help please!