Internet connection problem

Hello,
I am using window xp sp 2 having internet access. Recently i can't access internet anymore where as some of my colleague who are having the same setting with mine still get access to it. But then i still hav LAN connection though no internet access. Besides this, my ip setting are completely blank and an automatic ip address option is opted in the setting. I have tried to resolve it by entering the setting as it was before and as a result, goole page is opened but can't go further. There is also a log sign in the LAN icon. Please help.