panic: assertion: td->td_lwp == NULL || (td->td_lwp->lwp_flag & LWP_ONRUNQ) == 0 in _lwkt_schedule
I got this crash after about a week of uptime.
The machine was under moderate stress building a big c++ based project
and making use of swapcache.
Crash reports are available here: http://dl.zefyris.com/crash.12/
A complete core dump is currently uploading to this url.