Cannot browse…..DNS?

I have setup a DNS server (Active Directory Intergrated) on Win2k server, running Exchange 2000 and IIS. Everything works fine except for the fact that the server and clients cannot browse certain websites (websites they could browse by using a forwarder before DNS server was installed) I have flushed DNS on clients and the DNS Cache on the server but to no avail. I must be missing something? any suggestions appreciated.