Thanks for the information and noted.

A site, which gives information about hoax mails and other news confirms that the warnings are legitimate and should be taken seriously. Link is given below.

Warnings Claim Thousands May Lose Internet In July 2012

There you can visit this page

Detect | DCWG

and finally following link is a quick way to determine as to whether your computer is infected with DNS Changer or any malware. You will find instructions there to fix the problem.

DNS Changer Check-Up - Clean