PowerMac G4 unstable during pbulk

Hi,

When running a bulkbuild at some point (some hours or days) cpu usage drop to 0%. System is still responsive but it is in a weird state.I've tried to kill all process linked to pbulk and restart it but I'm always unable to kill one fetch process even as root with "kill -9". I can't even reboot because it seems nothing can kill this process.

nbqc1-mppc1# ps auxww | grep -v grep | grep fetch
root 6013 0.0 0.3 10916 2952 pts/1- D Mon02AM 0:00.10 /usr/pkg/bin/fetch -o slib-3b5.tar.gz http://swissnet.ai.mit.edu/ftpdir/scm/slib-3b5.tar.gz
nbqc1-mppc1# kill -9 6013
nbqc1-mppc1# ps auxww | grep -v grep | grep fetch
root 6013 0.0 0.3 10916 2952 pts/1- D Mon02AM 0:00.10 /usr/pkg/bin/fetch -o slib-3b5.tar.gz http://swissnet.ai.mit.edu/ftpdir/scm/slib-3b5.tar.gz

Restarting pbulk while have this "unkillable" fetch process ends in pbulk hangs ( cpu 0%) on the first package.

Furthermore, it seems some (or all) off my cronjob hangs :

nbqc1-mppc1# ps auxww| grep cron | wc -l
24

At least those one are killable.

I have nothing of interest in /var/log/messages...

Problem was there with NetBSD 8.0, 8.1 and 9.0. I'm also running netbsd on my ibook G4 as well as emulated qemu host and none of those have this issue.

On one hand I tend to think it might be an hardware issue with my PowerMac ( failing hard drive or ram)

However on the other hand i'm asking if there might be a generic issue related to this hardware.( Something kernel/module/driver related that might explain the unkillable process)

Has anybody experienced such issue with a PoweMac G4 ( or any other hardware) ?