System Restore
1. Log in to Windows XP using the administrator account. Click 'Start' and select 'All Programs,' then click 'System Tools' and click on System Restore.
2. Select the 'Restore my computer to an earlier time' option from the 'System Restore' window and click 'Next' to continue. Select a restore date from the calendar and then choose a restore point from the list. The restore point you choose should be the most recent date that you are sure the computer was functioning properly before the '0X0000009a' error occurred.

3. Click 'Next' to bring up a System Restore dialog window that will inform you of the changes that will be made to your computer based on the restore point you have selected. Click 'OK' to continue or 'Cancel' to select a later date.
4. Click the 'Next' button on the 'Confirm System Restore' window to start the system restore. Windows XP will automatically restart once the system has been restored. If the '0X0000009a' error still occurs while Windows XP is attempting to load, it may be due to a violation of the Microsoft Windows XP software license agreement.
Activation Wizard
5. Log in to Windows XP using the administrator account. Click 'Start' and then 'Run' to open a dialog window. Type 'regedit' in the field provided and click 'OK' to open the Registry Editor.
6. Expand the 'HKEY_LOCAL_MACHINE,' 'Software' and 'Microsoft' folders in the left-side navigational pane of the 'Registry Editor' utility by clicking ' ' next to each folder. Expand the 'WindowsNT' and 'CurrentVersion' folders as well and click on the 'WPAEvents' registry key listed under the 'CurrentVersion' folder.
7. Right-click on the 'OBETimer' registry value in the right-side pane of the 'Registry Editor' utility and select 'Modify' to edit this registry value. Change one of the numbers in the 'Value' text field and click 'OK' to save these changes. This will deactivate Windows so that you may re-activate Windows XP using the Activation Wizard.
8. Click 'Start' and 'Run' again, then type '%systemroot%\system32\oobe\msoobe.exe /a' into the 'Open' input field. Click 'OK' to open the 'Activation Wizard' and select 'Yes, I would like to telephone a customer service representative to activate Windows.' Click 'Next.'
9. Click the 'Change product key' and enter the Windows XP product key that came with your original copy of XP into the 'Product Key' text field. If your computer came with a copy of Windows XP installed, the product key may be printed on a sticker located on the back of your computer tower. Click the 'Update' button, then restart your computer once the product key has been updated.