wireless connection but no internet access

Hi - up until yesterday I could easily connect to wireless at work. When I went home I tried to connect using a dongle and this is when my problems started - I was definitely connected but could not access any websites as I kept getting the error message 'not connected to internet'. Now I can't connect with wireless at work (even though I'm connected to the network) or with the ethernet cable which is working fine on my desktop. Please help. I am using the safari web browser on a macbook.

It sounds as if your Internet connection has got the wrong settings somehow or the macbook is not detecting when it is connected to the network.

It is possible that your HOSTS file has got corrupted or changed, this can stop net access. Look for a file called "hosts", probably in a system folder called "etc", open that with a text editor, it should normally only have one line in it "127.0.0.1 Localhost". Any other lines suggest that it has been tampered with and may be the cause.

also I suspect that the dongle software may have changed your network settings to use a proxy server

I'm not sure where you'll find that in the airport settings though...

thanks for your suggestions. I will have a look and hopefully sort it out.