How to fix Windows activation problem

Step 1: Start the computer in safe mode
1. Start the computer.
2. After the computer runs the Power On Self Test (POST), press F8 repeatedly to open the Windows Advanced Options menu.
3. On the Windows Advanced Options menu, use the arrow keys to select Safe Mode, and then press ENTER.
4. Use the arrow keys to select the Windows operating system that you want to start, and then press ENTER.
5. When the computer is running in safe mode, log on by using an account that has administrator rights and permissions. Then, click Yes in the message that states that Windows is running in safe mode.

Step 2: Start Registry Editor
Click Start, click Run, type regedit, and then click OK.
Step 3: Remove the RESETS registry subkey
1. In Registry Editor, expand My Computer, and then expand HKEY_LOCAL_MACHINE.
2. Expand SOFTWARE, and then expand Microsoft.
3. Expand Windows NT, and then expand CurrentVersion.
4. Expand Winlogon, and then expand Notify.
5. Under Notify, right-click RESETS, and then click Delete.
6. Click Yes to confirm the removal of the RESETS subkey.
Note Do not exit Registry Editor. You must use Registry Editor in "Step 4: Modify the registry to deactivate Windows."
Step 4: Modify the registry to deactivate Windows
1. In Registry Editor, expand My Computer, and then expand HKEY_LOCAL_MACHINE.
2. Expand SOFTWARE, and then expand Microsoft.
3. Expand Windows NT, and then expand CurrentVersion.
4. Under CurrentVersion, click WPAEvents.
5. In the right pane (topic area) of Registry Editor, right-click OOBETimer, and then click Modify.
6. Click to put the pointer in the Value data box. Then, modify any character that appears in the Value data box.
7. Click OK.
Note This step deactivates Windows.
8. Exit Registry Editor.
Step 5: Rename the corrupted Windows activation file
1. Click Start, click Run, type cmd, and then click OK.
2. At the command prompt, type the following command, and then press ENTER:
ren %windir%\system32\WPA.dbl wpa.old
This command renames the WPA.dbl file to WPA.old.
Step 6: Determine the CD or DVD drive letter
1. Insert the Windows CD.
2. Click Start, and then click My Computer.
3. Note the CD drive letter or the DVD drive letter that appears under Drives with Removable Storage. You have to use this drive letter in the next step.
Step 7: Replace the corrupted Windows activation file
1. Click Start, click Run, type cmd, and then click OK.
2. At the command prompt, type the following command, and then press ENTER:
expand F:\i386\wpa.db_ %windir%\system32\wpa.dbl
In this command, replace F: with the letter of the drive that contains the Windows CD.
expand d:\i386\wpa.db_ %windir%\system32\wpa.dbl
This command extracts a copy of the Wpa.dbl file from the Windows CD. Then, it puts this file in the System32 folder of the Windows installation.
3. Examine the output that appears at the command prompt. If the command runs successfully, information that resembles the following appears:
Microsoft (R) File Expansion Utility Version 5.1.2600.0 Copyright (C) Microsoft Corp 1990-1999. All rights reserved. Expanding d:\i386\wpa.db_ to c:\windows\system32\wpa.dbl. d:\i386\wpa.db_: 2222 bytes expanded to 2126 bytes, -5% increase.
4. Type exit, and then press ENTER to exit the command prompt.
Step 8: Remove the files that are associated with the script
1. Click Start, and then click Search.
2. Under What do you want to search for, click All files and folders.
3. In the All or part of the file name box, type the following, and then click Search:
reset5.exe; reset5.dll; reset5.dat; reset5.dt*; srvany.exe
This action performs a search for all the following files:
* Reset5.exe
* Reset5.dll
* Reset5.dat
* Reset5.dt*
* Srvany.exe
Note If you use a different search tool such as Windows Desktop Search, use this tool to search for each of these individual files.
4. In the results pane of the Search Results dialog box, right-click each file, and then click Delete.
5. Click Yes to confirm the removal of the file.
6. When you have finished removing these files, exit the Search Results dialog box.
7. Restart the computer and let Windows restart in normal mode.
Step 9: Reactivate Windows
1. Click Start, point to All Programs, point to Accessories, point to System Tools, and then click Activate Windows.
2. If the Windows Product Activation Wizard prompts you to activate Windows, follow the instructions in the wizard to activate Windows.
3. Restart the computer, and then repeat step 1 of "Step 9: Reactivate Windows" to start the Windows Product Activation Wizard again. You take this step to verify that the wizard does not prompt you to activate Windows again.
4. If the Windows Product Activation Wizard displays a "Windows is already activated" message, click OK to exit the wizard.
or

Use Activation Tools