On my laptop i have a weird problem, none of my web browsers can access the internet.
But msn messenger and Thunderbird are perfectly working. I have a wireless broadband connection. My guess is some viruses may block my port:80.
I would suggest checking your DNS. Open command prompt and try to ping google.com, if that doesn't work try pinging 126.96.36.199, which is a google.com IP. If it doesn't work for the address, but it does for the IP, you probably have a DNS issue.
You could try to manually set your DNS to something new like 188.8.131.52 which is google's new DNS, or 184.108.40.206 (not google)