I have 3COM US ROBOTICS modem 56K FAx and it works via phone line and it connects and icon appears that network is connected but i am unable to do anything on net, in fact no website open and no software updates but modem connects clearly (Windows Xp sp2)

Is this a new problem? Did it ever work?

If new try a System Restore to a point prior to the problem:

start > All Programs > Accessories > System Tools > System Restore

There is no restore points. The problem arises when i scan all my computer and then some viruses (Nimda etc) found and i cleaned then many exe files (like of games) stop to work and modem also. I reinstalled window also but problem exists only with connecting. Thanks if you help.

Did you reinstall all your motherboard drivers?

Yes i have done it... what can i do my modem works but unable to connect to net

Try clicking start Run... cmd

Here type (or copy/paste): ipconfig /release

Enter then type (or copy/paste): ipconfig /renew

What happens? What messages (if any) do you receive?

kindly somebody help

when i write it simply gives
Windows Xp ip configuration

If you have not already done this, try this simple steps to just make sure: In IE, form Tools menu, click Internet Options, click Connections, under Dialup and Virtual Network Settings, click Settings, put a check mark next to Automatically detect settings; also, remove the any checkmark from next to Use a Proxy Server for This Settings.