internet will not display any pages,pop sever not found.

Hello I hope someone can shed some light on this problem??,If not
perhaps you can point me in the correct direction.

I have windows pro xp + service pack 1

I can dial on to the internet no problem,even with 2 different isp's
but
I get this fault: the page cannot be displayed

also messenger won't work

mail fails to find the pop server

no pages can be displayed.

I have tried the following

new dial up software
uninstall ie 6
reinstall ie 6
reinstall service pack 1
repair win xp pro
checked for viruses
reset all internet options to default
run ad-aware 6.0
Hope you can help.