sleepqueue assertion panic and hang

I haven't seen any reports of this yet, so here goes.  I'm getting
an assert panic at odd intervals.  Sometimes I get it with the initial
login prompt.  I have also gotten it in the middle of the night during
a rebuild of mozilla.  And my system as been freezing when I start
mozilla or thunderbird and even once starting xdm.

panic: Assertion td->td_flags & TDF_SINTR failed at 
/usr/src/sys/kern/subr_sleepqueue.c:761
at line 761 in file /usr/src/sys/kern/subr_sleepqueue.c
cpuid = 1;
Debugger("panic")

And then it freezes.  Reset is the only way out.  I have also seen cpuid
= 0.  (It is a dual processor P3).  I have rebuilt the kernel and world
from current.  I have no back trace because it freezes instead of
dropping into the kernel debugger.

I could send more information if my email client (thunderbird) was
working...

Danny Zerkel
dzerkel_at_columbus.rr.com