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I recently reformatted my hard drive (virus) and entered an incorrect product key. I needed to validate my system and it was rejected. I didn't realize my correct key is on the side of my pc . Is there a way to correct this without reformatting ?


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Before you execute harrymc's solution: any chance to enhance the question with the precise error message Windows gives you? – Arjan Sep 30 '09 at 10:24
Hi, It wasn't an error message per se. I was downloading an audiobook from our local library and software needed to be installed. After that, windows media needed to be validated. During that process microsoft rejected the validation process – jeffr72 Sep 30 '09 at 23:50
Ok, then, for the sake of other people searching for an answer to the same problem, it would still be nice if the exact "please validate" message was in the question... Anyway: solved, so please accept harrymc's answer to indicate that. – Arjan Oct 1 '09 at 10:23

You may How to Change the Product Key in Windows XP SP3:

Method 1: Change the Product Key Using Windows Product Key Update Tool

  1. Download and install the Windows Product Key Update Tool.
  2. Launch the Windows Product Key Update Tool.
  3. Enter your valid Windows XP product key and then click "Next."
  4. Select "Restart Now" and click "Finish" to complete the process

Method 2: Manually invalidating

Invalidate the existing Windows serial number

  1. Click Start, and then click Run. In the Open box, type Regedit, and then click OK.
  2. In the left pane, locate and then click the following registry key:
    HKEY_LOCAL_MACHINE\Software\Microsoft\WindowsNT\Current Version\WPAEvents
  3. In the right pane, right-click OOBETimer, and then click Modify.
    Change at least one digit of this value to deactivate Windows.

Enter the new Windows serial number

  1. Click "Start" and go to "Run." Enter the following string:
    %systemroot%\system32\oobe\msoobe.exe /a
  2. Click "Yes, I want to telephone a customer service representative to activate Windows" and then click "Next."
  3. Click "Change Product Key."
  4. You will now be able to enter the valid serial number for your Windows XP.
  5. Press "Update" and close the window.
  6. Now restart your computer. Your version of Windows XP should now be updated with the new serial number.
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It almost worked. Your constructions resulted in a message " your copy of windows is activated" I believe I need to go into the registry and change 1 number to deactivate windows and then use the instructions you gave me to activate windows. – jeffr72 Sep 30 '09 at 23:52
You're right. I've edited the missing first step into the answer. – harrymc Oct 1 '09 at 7:47
I thought that the way to do this was to use the Windows Product Key Update tool. – djangofan Jan 26 '11 at 5:21
@djangofan: You are right - my answer was no longer up to date. Updated. – harrymc Jan 26 '11 at 7:04

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