Connected to Wireless network but cannot display pages in browser

I have a very annoying problem and I am looking for a solution please.
I have a new Sony Vaio that will connect to my broadband at home but not in the office.
It shows me in the office that i am conected to the wirelss network but I cannot get on the internet. (i have windows 7)

I have called Sony and they asked me to download an update but I can’t even connect through an external internet dongle now!

can anyone help?