Can't connect to internet

Hello people i'm getting furious with this. Somehow this stupid installation with 2 days can't connect to the internet. Yesterday was fine but today nothing happens. Emails, IM's nothing. It's just if a firewall blocked everything but I don't have any rules in Iptables. In the private network it works fine, only the internet fails and all it's services. Another stupid thing: the network configuration applet is in the "Preferences" tab and not in "Administration" so I cannot change it from GUI. So no password is required and of course no changes are applied. I had to dig in the interfaces file. What are this guys from Cannonical doing. I think this is inadmissible. Help me please.

PS: I use Ubuntu for 3 years now and things like this never happened to me. The OS was always very stable.

What version of Ubuntu are you using?

Sef said: What version of Ubuntu are you using?

I had and still have Intrepid. I re-installed today in the mourning because i needed the box working. But I still need answers because that's not normal and I am curious. Thanks for reply

You say you cant connect to the internet.

• are you able to ping?
• do you have a network adress? see ifconfig

The private network worked very well without problems: samba, printing, etc. Only the comunication to the internet and all it't services was broken. Ping to outside my network was impossible however within the network was fine. I made something on Friday: i've changed my hostname. But on that day the net worked without problems even after a reboot. Was that incident caused by the changed os the hostname? I was completly blind on that. Thanks.