Microsoft Vicious Virus re: windows 7 Internet

In 2008 I bought a Gateway desktop computer from Walmart in Vancouver, Canada. The computer came with Windows 7 OS and other preloaded software. I have used this computer for the past 7 years without much problems. On July 22, 2015 I had a screen notification saying that I am not using a genuine copy of Windows 7 and to call a stipulated toll free number to get a genuine copy. I ignored this notice. After about an hour another notification appeared stating that my computer is due to be shut down. In a little while the computer shut down. I tried using the Gateway recovery programs and others but the computer was truly frozen. I took it to a professional technician who failed to even format the hard drive. He had several other computers with the same problem and he had recovered some files in one of them but they too were corrupted and unusable. This is a virus that bypasses the traditional antivirus programs and corrupts your entire system. I had to dump the Gateway and buy a new computer. This is a warning for all computer users to be alert. As consumers we have no recourse!!