> I am still occasionally getting a freeze of my system. In general
> it seems to occur under heavy load during compile of /usr/src
> (make build) along with a second activity like 
> dd if=/dev/zero of=/tmp/junk bs=1024k count=50
Sounds more like a hardware failure than NetBSD related problems. One
thing
you could do is try "memcheck", a program that does intensive memory
tests.
It is creates a bootdisk, so you need no DOS or something.

Another thing you could do, if you have the resources, is swapping hard-
ware. E.g. the video adapter, ethernet etc. Replace or remove step by step
whatever you can replace or remove.

Good luck!
   Alex.