Not a genuine copy

Hi I have had my laptop for over 2 years now, with no problems, but today it is saying that my copy of Windows vista is not a genuine copy, even though it is, and has been working since I bought the laptop new over 2 years ago. It has allowed me to use the computer to get online, so that I can buy a genuine copy! But it hasn't opened my desktop up, I just have a black screen. I downloaded Hijack this, but now it won't let me run it, as I can't get to my desktop to find it. Can someone please help me, and tell me how to sort this problem out. Thanks Lisa

You DO NOT need to buy a legitimate copy. The copy you have is legitimate.

You need to contact Microsoft, see here: How to activate Vista by phone

I just re-read your post and now I'm a bit concerned that you may have picked up a virus of some kind.

Try Microsoft first, but if that doesn't work, please go to the Malware area of WhatTheTech, read the pinned posts at the top then follow directions.