This problem occurs because Windows XP is in a state that prevents WGA from accessing the product ID (PID). This state may occur for any of the following reasons:
The %windir%\System32\Wpa.dbl file is missing or corrupted.
The security settings or the attribute settings for the %windir%\System32\Wpa.dbl file are incorrect.
Some downloadable tools have moved or modified the product ID.
The product ID value in the registry is missing or corrupted.
One or more of the following files may be an incorrect version, or they may be unregistered:
Step 1: Verify that the validation check is failing
Click Start, click Run, type oobe/msoobe /a, and then click OK.
Note There is a space between msoobe and /a.
The Activate Windows dialog box appears. Follow the instructions that appear on the screen to activate Windows XP.
If you still receive an error message, go to step 2.
Extract the LegitCheckControl.cab file to a temporary directory on your computer.
Copy the Legitcheckcontrol.dll file in the temporary directory to the %windir%\System32 directory.
Click Start, click Run, type cmd, and then click OK.
Register the new version of the LegitcheckControl.dll file by typing the following command at the command prompt:
regsvr32 %windir%\system32\legitcheckcontrol.dll
Restart the computer.
After the computer has restarted, perform step 1 again to determine whether the problem still exists. If you still receive the error message, go to step 3.
Step 7: Verify the security settings for the Wpa.dbl file
In Windows Explorer, locate the %windir%\System32\Wpa.dbl file.
Right-click Wpa.dbl, and then click Properties.
On the Security tab, click to select the SYSTEM group. Verify that the Allow check box for Full Control is selected. If Full Control is not selected for the SYSTEM group, select it, and then click OK.
Perform step 1 again. If you still receive the error message, go to step 8.
Note In Windows XP Home Edition, the Security tab appears only when the computer is running in safe mode. Also, In Windows XP Professional, the Security tab appears only when the Use the simple file sharing (recommended) check box in the Folder Options dialog box is not selected.