howto debug a complete hard reset

hi there,

i'm running HEAD on amd64 and experienced some really annoying resets during
the last couple of months.

when i do 'sysctl -a' or 'sysctl -a|grep bla', my whole system does a hard
reset. no core dump gets produced.

isn't there a way to find out which sysctl variable is causing the reset?

cheers.
alex