My hardware knowledge isn't good, but I would guess your graphics hardware is involved because nothing is output to the screen. Every crash I have experienced with FreeBSD something is ouput to the console.
I suppose if you really bored you could recompile a default kernel, make sure it starts crashing and then change one thing in your kernel configuration and recompile. Repeat until the crashes stop then you'll know exactly what option stops the crashing.
Another thing you can do is follow this two part article
, part 2 is here
to get a core dump and examine it. As the article suggests you can submit it to the FreeBSD mailing lists and see if it catches the interest of a developer.