Caching only nameserver breaking

[Charles Derykus]

Our caching only nameserver running on an RS6000, rev 3005 has started to
break intermittently. It is also a resolver. /etc/resolv.conf is listed
below:  
nameserver	127.0.0.1
nameserver	128.207.254.223
nameserver	128.207.254.44
nameserver	136.240.1.21
domain	ca.boeing.com

When the nameserver breaks, it stops resolving from the local nameserver
cache and looks only to /etc/hosts.  It also refuses to query other
nameservers.

The really weird thing is that it seems to get well after an indeterminate
amount of time.  Suddenly, the local nameserver starts resolving, apparently
none the worse for wear.

Sometimes I can stop/restart named to make it well, but this doesn't always
work.

Has anyone seen this or have any theories?

Any help greatly appreciated.

Charles DeRykus				Internet:   ced at bcstec.boeing.com
Boeing Computer Services		UUCP:	    ...!uunet!bcstec!ced
Renton, WA.  M/S 6R-37			(206) 234-9223