[ale] DNS issues

[jimmyc at speedfactory.net (Jim Philips)]

I made numerous upgrades on my Slackware box earlier this week, 
including BIND. Now DNS seems to have gone crazy. Sometimes I can't 
retrieve mail. When I try the following:

dig mail.speedfactory.net

I get a message back saying no servers could be reached. The DNS servers 
in /etc/resolv.conf are the correct ones for Speedfactory, as far as I 
know. This is what I have:

nameserver 66.23.208.138
nameserver 66.203.208.142

But some addresses just can't be found even when I have a perfectly good 
PPP connection. This issue doesn't exist in Windows (which I'm using 
now) so it has to be a Linux issue. Any further ideas on what I should 
check?