HP laptop not able to connect to the internet

The internet on my HP dv6500 laptop was working fine till yesterday night. Today morning however, all the browsers are unable to connect to the internet. IE shows “Internet Explorer cannot display the webpage” followed by a host of possible reasons which include DNS servers not being reachable.
But I’m able to connect to the router homepage and change all the settings over there. I’m even able to ping the DNS servers which are shown in the router homepage. My wife’s laptop is of the same make, and has no problem connecting. I tried all the automatic solutions VISTA had to offer but still no luck. Can anyone tell me how to diagnose what’s wrong??
Thanks in advance

srikant