I can only access pages on the Net by using the numbered IP addresses. This is both on Dial up and BT Broadband and can't download or send messages on Outlook Express both on Broadband and dial-up
Any ideas as have tried just about everything.

Are you using a router? If so, you should check if your DNS name server settings are correct. If not, use Command prompt to release and renew your IP settings ("IPCONFIG/RELEASE" and "IPCONFIG/RENEW" I believe). If this doesn't work, contact your ISP (Internet Service Provider).

Any more ideas

Try takeing a look in your hosts file.

Click Start
Click Search (or Find for 98 and older)
Search for hosts
Open up the hosts file in the system32 folder with notepad
Check to see if the file looks like this:

# Copyright 1993-1999 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
#      102.54.94.97     rhino.acme.com          # source server
#       38.25.63.10     x.acme.com              # x client host
127.0.0.1       localhost


for more info on the hosts file go to:
http://accs-net.com/hosts/what_is_hosts.html