kern.maxpipekva exceeded, please see tuning(7).

I've got a 5.2.x machine which has hung and is giving the message
'kern.maxpipekva exceeded, please see tuning(7)' on the console
whenever anyone tries to open a tcp connect to it.  Does anyone
know what this tweakable is about and what might cause it to be
"exceeded"?  The machine has been running fine for 6 months.

Joe
-- 
Josef Karthauser (joe_at_tao.org.uk)	       http://www.josef-k.net/
FreeBSD (cvs meister, admin and hacker)     http://www.uk.FreeBSD.org/
Physics Particle Theory (student)   http://www.pact.cpes.sussex.ac.uk/
================ An eclectic mix of fact and theory. =================