Windows 7 ipv4 autoconfiguration - cannot connect to internet
Actually it was the problem with my Internet Provider. It was a DHCP configuration problem. Probably he had mapped the same IP to 2 different MAC addresses or something. I only know that the problem was in configuration of DHCP server on the service providers side. So in future if anyone gets this kind of problem, be sure to check your DHCP configuration of mapping between MAC and IP address first.