9.3.1 : CRASH: server.c:1942: INSIST(zoneview != 0) failed

[Thornton Vale]

I recently posted about a problem I was getting with crashes on 9.3.0 and
was advised to upgrade to 9.3.1 . I've done so but now my daemons are
crashing with a different error message.
Currently I run a reload every half hour to update new zones ( the servers
have around 20,000) . What happens is that if I restart a daemon for some
reason then 2 or 3 reloads later it will crash on a reload.

21-Nov-2005 19:46:24.856 loading configuration from '/etc/named.conf'
21-Nov-2005 19:46:42.001 server.c:1942: INSIST(zoneview != 0) failed
21-Nov-2005 19:46:42.002 exiting (due to assertion failure)

However another restart doesn't usually crash. The first crash will happen
more than 50% of the time (2 servers out of two last time). Any ideas?