If you have an HP computer (or perhaps even another brand) with a copy of Windows Vista that suddenly tells you that it’s not genuine you might be pleased to hear that your issue may be resolved with a simple hotfix from Microsoft.
From the Microsoft Website:
This problem may occur because a specific system setting is removed when a program runs with administrative credentials. The removal of this system setting may cause a BIOS validation check to fail. The BIOS validation check is part of the system activation process. Therefore, you may be prompted to activate Windows Vista, even though the system did not previously require activation. For example, this problem is known to occur when you use Intuit QuickBooks 2007. However, this problem may also infrequently occur when you install other programs or device drivers.
You can find the hotfix at this page. Also make sure that you’re running the latest Service Pack (which at the time of this writing is Service Pack 1).
Cheers! As always let me know how it goes in the comments section!