one more thing which is quite surprising over here that if I ping pc (1) from pc(2) it shows REQUEST TIMED OUT but if I restart pc(1) while shutting down.... the pc(1) starts pinging on ipv4 and than again till it is on CTRL+ALT+DELETE it does ping than it stops after logging in. I am sure its not because of a virus issue but I have already tried fixes like PREFERRED IPV4 ON IPV6 ,still didn't resolve the issue.