Can only access Debian website through proxy

[pierre poulos]

Using Iceweasel, Google Chrome and Lynx I cannot access http;//
www.debian.org or any of the mirrors without using an external web proxy. My
isp says they can access fine on their own machines. My wife's
computer running Firefox on WinXP sp3 on the same connection also works
fine. I have had to change my apt sources list as it was unable to access
the
security updates. What's wrong with my machine.
I am running lenny current.