I want to know the actual contents of the /etc/resolv.conf. And you already have hdclient installed or you wouldn't be getting a DHCP address. The dhclient program is /sbin/dhclient. For more information on it do a "man dhclient".
The /etc/resolv.conf file contains the list of DNS servers that your clients should use to resolve addresses. During the time that your name resolution fails can you actually ping these servers? If so, can you do this on the command line:
Change "xxx.xxx.xxx.xxx" above to the first DNS server address listed in your /etc/resolv.conf. It should return the IP address for
www.google.com. If these DNS servers are your providers DNS servers I would like to know their addresses (please copy/paste the contents of /etc/resolv.conf into a message). If I know the addresses I might possibly be able to see if there is anything wrong with them from my end.