A little background: NW6 SP3, named.nlm v 5.10.09 (2/12/03)

We are experiencing some odd DNS issues. Basically, every so often, the
NetWare server just stops resolving certain external host names. Not all,
just some, like www.businessdirect.att.com and windowsupdate.microsoft.com.
I've tried setting up DNS so that our internal DNS server will forward to
our ISP's DNS server, tried using a Linux box in the DMZ as a forwarder and
even tried setting up DNS such that the NW server forwards any external
requests to the root servers. Any way I try it, it won't resolve these
specific hosts. I've tried unloading and reloading named, to no avail. The
only real solution I've found to the problem is to reboot the server. I'm
rather stumped. Its almost as if the entries get cached as being dead and
never clear. I tried loading named with the -pa switch, but I'm not sure if
that has any effect in NW 6.

Any ideas would be appreciated.