hi,
i think this time u will help me.i tried so many times no body help me.
i posted earlier some friends tell me few tips that did not work.
i have mandrake and KDE environment.i am using mozilla.
i using two systems near by,one is connecting to internet and another not.
i used same proxy and port number.the error was

the connection was refused when attempting to contact the proxy server you have configured
please check your proxy seetings and try again"
sir this was the error for this what should i do ?
thanks for advance.

Does the computer that connects to the internet have a firewall running on it ??

If it does then you will need to change the firewall settings to allow your other computer to talk thru your firewalled proxy

yes sir,i saw in mandrake linux control center.the firewall in on condition.
and how can enable firewall proxy.

First , turn off your firewall then try to connect using your second PC . I f this works then we know for certain that its your firewall settings