Hi, About 6 months ago, I bought a computer which had windows 7 ultimate already and it worked fine. Then, last week, it came up with a message saying it wasn't genuine and on the desktop (which is permanently black) it says "Windows 7 / Build 7600 / This copy of Windows is not genuine". Will I have to buy a new copy? If I do, can I get the upgrade or do I have to get the full version??

6 month. If this is not a message, which disappear a short time later, I am afraid, that somebody else installed Windows 7 with the same product key and therefore the concurrent use resulted in the message you see. So yes, you may have to buy a new copy. Updates are only supported from lower level versions (i.e. Vista, Windows 7 Home editions), so that I cannot say reliable, that installing an upgrade on top of the version or simply using the product key will work (since I have no update version in my hands, testing is not possible). It would also only be regular, if you have one of the Windows versions, for which updates can be purchased. Best greetings from Germany Olaf