On Wed, 16 Mar 2016, D'Arcy J.M. Cain wrote:
Can anyone suggest any other avenues to investigate?
Have you tried running a kernel with DDB enabled ? If the machine will handle it, horsepower-wise, I'd turn on that and make sure all your debugging symbols are rolled up into your kernel image (ie.. cc -g which you can set by un-commenting the makeoption in your kernel config). Then when the thing falls over again, get a backtrace from it.
If you get really angry and motiviated you might try a serial line kernel debugger since it seems the bug might lockup the keyboard and mouse. There are some instructions for that here:
http://www.netbsd.org/docs/kernel/kgdb.html Swift