nameserver not responding (servfail)

[David Cake]

	I have a standard debian bind9 installation. It is on a 
virtual server, so it is possible ram and disk are a bit tight, but 
the box is doing very little else apart from running bind currently. 
It is serving a bunch of domain names, about 60, a lot of them from 
zone files I've generated with a script.
	It loads all domains fine on startup, and sends and receives 
notifies, but any attempts to lookup domains from the server itself 
seem to fail, returning servfail.
	Nothing in the logs. I've tried turning debugging on, didn't 
seem to help, I might be doing it wrong.
	Every so often I can coax it into temporary life, with 
various voodoo methods, but nothing seems to work consistently or for 
long. I suspect I am running out of some resource, but what?
	Cheers
		David