Weak CMOS battery

For several weeks i had been facing issue with my BIOS settings that my PC never remembered the current date and time. The situation has become worse that windows is not even booting up with a weak CMOS battery. It just freezes in that blue logon screen. Even Safemode boot is not happening with the boot freezing at mup.sys. On the other hand Linux boots up properly.
It seems that with a Weak CMOS battery windows will not boot.

Its high time that my motherboard needs CMOS battery replaced.

DNS configuration in ubuntu

I tried to boot with Ubuntu live CD. Ethernet configuration was fine. ping to any internet sites worked but could not browse through browser since there was some DNS server issue. The DNS server was not resolved properly. Opened the Dlink router administration page through browser to find the DNS server IP address. There is a file called /etc/resolv.conf. (you might need to do sudo to edit this file). Replace the nameserver IP address with the DNS server IP address in the Dlink page. Restarted the browser and it started working. Thanks to Vijairaj for guiding this out.