Hello Dear,
Just do one thing. Follow these steps very carefully i think it may cause your prob. to be solved properly.

Step 1 Open the terminal window.

Step 2 Type command "netcardconfig" and press enter.

Step 3 After some time you will be prompted whether you want to use DHCP or some like same in a new window. Click on "NO" to this first question.

Step 4 Now It will ask for the IP. type your ip address and click on "O.K".

Step 5 Same way subnet, Default getway and in Getway give the ip of your proxy server. and in DNS give the ip of DNS server. -->You can obtain this from your ISP admin. and Your broadcast ip address that you have to calculate either manualy or by using a S/W called ip caculator.

after entering all the required ip your machine is in n/w and you can access internet.

Long live "Live linux"