Invalid Windows 7 licence serial key

Question

I get this popup telling me that my windows 7 64 Home premium is not valid, that it is not real and that I have to get the real deal. Furthermore microsoft asks me to match this windows i use with theirs - leading to them wanting me to buy it.
Again.
The thing is, my Windows 7 is real, it came with the computer and I have not changed it, and has been working perfectly fine for over a year until a few weeks ago, when this notification showed.
Now I am having all kind of trouble, most of them internetbased seeming the computer turns of my internetconnection all the time.
What do I do?
I am somewhat a noob and have not messed around with computers since XP.
Best regards // Ican

Answer 1

I'm not sure that this is what you have done but if not try it:
Call Microsoft Using Manual Phone Activation
1. Open Windows Activation - click the Start button, right click Computer, click Properties, then click the option to activate Windows now or change your key.
2. Click Show me other ways to activate.
3. Type your Windows 7 product key, and then click Next.
4. Click Use the automated phone system.
5. Click the location nearest you from the drop-down list, and then click Next.
6. Call one of the available phone numbers listed.
7. Do not select any options and wait for a person to pick up, then explain what happened.