Help !!! Can`t connect to internet using LINUX machine

[Nawasthi]

Hi guys...

Only problem right now with me after successfully
configuring Samba and windows is that.

I cannot access internet from LINUX machine.

It was working fine when I installed Linux and configured it to windows
but after some time I don`t know when Internet access
started getting "Network error occurred. unable to connect to server(TCP
Error: Network is unreachable)"

If anyone have a wonderful ideas about how to fix it please
mail me at nawasthi at vanguardsolutions.com

I can access any machine within the network but no machine outside the
network
(using Netscape navigator on the Linux machine)

Thanks everone
Nishant