dig works, but nslookup fails?

[pwolfe at qred.quintiles.com]

I currently have BIND 4.9.4, and will be upgrading, almost immediately, however
I have a question.

My current server fails with nslookup on some sites, so I downloaded dig. About
time you say. I agree!

Question: My nslookup fails, but DIG resolves the site:

Example sites I'm having trouble with are:

www.go-fly.com
www.pharmweb.net

Is the resolver the problem causing nslookup and the named server to fail? I
have read that DIG uses other resources for its resovler. Is this true?

If that's the case, can I simple upgrade my resolver somehow?

Thanks in advance.