Google Nexus S — Bad Reception

I have a Samsung Nexus s 4g and when I go to the internet, I go down to either 1 or zero bars and can not make connection. Has anyone got any idea's?? I have powered down the phone and when it comes back up I have 5 bars, but when I go to a browser it goe's to zero bars.

Turned out to be a 4g outage for 2 days. All works now....

it does happen when your service provider is down, you should have tried wifi