SPRINT EVO NOT CONNECTING TO SPRINT NETWORK! HELP?

My htc evo is not connecting to the internet browser every time i put google.com or something it say it can not display but its weird because i can chat on aim and look at my emails. its just the browser and when i look up in my settings at my network it says it is disconnected i have tried numerous times to try to connect it but it does not want to connect to the sprint network what so ever! please help and yes i have unlimited internet