My laptop wont open pages on the internet.?

I have a wired PC to my wireless router and it works fine. I plug in my laptop to the same router and it will go on line and pull up some sites but wont pull up Gmail, yahoo, etc.. It starts and just stays in perpetual loading stage. I am using mozilla as well as IE and neither will pull up the sites i said i cant go to my mail or anything.. PLEAS HELP......