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I bought Windows 7 Professional Retail which I installed on my laptop. Now I've decided to move it to be on my desktop PC, so I uninstalled Windows from my laptop, restoring the original OS that came with the laptop (Vista Business), and installed Windows 7 on my desktop PC. The problem is that I cannot activate my copy of Windows 7 on the desktop PC. Every time I try to activate it I get the error message:

The product key you typed cannot be used to activate Windows on this computer

and the code of the error is:

Code: 0xc004c008

Description: The activation server determined that the specified product key could not be used.

How can I solve this problem?

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This Microsoft Support page has information on the error code. It states under the heading for your error code:

This issue may occur if the KMS key has exceeded the activation limit. KMS keys will activate up to 10 times on six different computers.

If you need more activation times, contact the PA Call Center.

It looks like you have to ring Microsoft Support.

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I don't think exceeding the activation limit is the problem because this is the second time I try to acivate windows the first one was when I install it on my laptop and on that time it succeeded. – Abdullah BaMusa Apr 10 '10 at 19:29
@Abdullah, it looks like Win7 activation is more sensitive than it should be,…. Try doing what Ronnie Vernon indicates in the link above. – hyperslug Apr 10 '10 at 19:50
@hyperslug: Thank very much, I solved the problem by calling the automated Toll free phone number for my country. WOW.. What a relief – Abdullah BaMusa Apr 10 '10 at 20:40
up vote 2 down vote accepted

I solved this issue by calling the automated tool free phone number service for the country where I live and just followed the instructions. Thank you all who tried to help me.

  1. Press the Windows Logo Key+R. This will bring up the Run dialog box.
  2. In the Open box, type "slui 4" and press OK. This will start the manual activation wizard.
  3. Select your Country in the drop down menu and click Next.
  4. The wizard will display a Toll Free phone number. Leave the wizard open on the computer and call that phone number.
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