Windows 7

[Shirleyx]

A few months ago I bought an Advent lap top with Windows 7 from PC World. No problems until a few days ago when I logged in and there was a message "Windows 7 Build 7600 This copy of Windows is not genuine". Any suggestions please and has anyone else come across this problem. I can still use the computer.

[Buenchico]

While that's the exact wording of a genuine message from Microsoft, the message itself is almost certainly fake. A quick Google search shows (as well of loads of posts relating to genuine problems with fake software) that there's some malware finding its way onto lots of PCs, producing exactly the same message as you're seeing.

If you've got an anti-malware application on your PC (such as Ad-Aware, Spybot Search & Destroy, or the relevant component of a commercial security suite - such as Norton 2010) run a full scan now. If not, download and run the free version of Malwarebytes' Anti-Malware:
http://www.malwarebytes.org/mbam.php

Chris

[Aquariel]

In addition to Chris' answer, I also had this message and my PC was definitely virus- and spyware-free. The problem with mine was that I had installed a dodgy version of MS Office which was generating the non-genuine message, so I got rid of it and installed Open Office instead, which is just as good and free.