BIND t-shooting?

[Ken D'Ambrosio]

Okay, it's time for true confessions: I kinda suck at BIND; I'd been 
using other DNS servers for years, and JUST rolled out my own BIND on 
two different servers recently... and it's working great.  But I also 
just got two *other* servers with BIND installed by Ubuntu.  Doing local 
lookups fine on its own domain, but when it goes to do a query upstream 
against 8.8.8.8 (Google), it can take *FOREVER*.  I've had repeated 
requests for yahoo.com fail for over two minutes; I haven't had any 
requests succeed in under 15 seconds.

Any pointers on what I should be looking for?  Afraid Google is kinda 
failing me.

Thanks!

-Ken

P.S.  A tcpdump shows me that the IPv4 reply is essentially 
instantaneous, but then -- even though I didn't ask for IPv6 -- the AAAA 
reply comes back much later.  I've tried everything I can find to 
disable IPv6 (both in-kernel and in the named.conf file), to no avail.  
I don't know if this is relevant to my issue or not.