I can enter on the net only if I am root. My other user cannot acces the net. I am behind a firewall, in a proxy... inside a net (big one, about 300 people). I don'n like to be root to enter in internet !

you need to give a *LOT* more information. what are you doing to "enter the net"??? what applications? what error messsages are you getting??

I set the network parameters according to my local net. When I run mozilla as root, I enter in the internet on my default window and I can navigate. If I try to run mozilla as normal user, I receive message error: the page cannot be displayed (classic error message).
I run on suse 10.2

while logged in as non-root , open YaST2, and get to your firewall, and disable it. Then try accessing the internet as a regular user. If you have access then you have to configure your firewall properly so it will allow regular users to access the internet. Now if you still can't access the internet, even with your firewall disabled, then it isn't your firewall. You will have to check your network setup again, and make sure everything is set up properly. Are you behind a router or a switch? try the mentioned things, and post more info about what happened.
Good Luck

Did you check the proxy in mozilla?

Yes use Yast. Yes use the Firewall configuration resolve. Please also check the Users in Yast. Root may have dialout privileges that User? needs. Also,...go to Security and Users and click on User Management. Click through, and check the box that says "dialout". Click "Accept" and "Finish".