Window Product Activation Error Code: 0x80090006

Try this:
http://support.microsoft.com/default.aspx?scid=KB;en-us;q310794

If the above doesn't work/help:

You may wish to try a reinstall or try a repair:
http://www.michaelstevenstech.com/XPrepairinstall.htm

Safe Mode w/ Command Prompt

regedit

HKEY_LOCAL_MACHINE\Software\Microsoft\WindowsNT\Current Version\WPAEvents

Double click "OOBETimer" on the right, and select 1 digit to modify......

Once the registry editor is closed, type the following.....

"%systemroot%\system32\oobe\msoobe.exe" /a

The activation window should come up.... If the Internet Method doesnt work, select the Telephone option, and call the sweet folks at MS.....

Hopefully you should be ok....

"Error Code: 0x80070002" error message cites license-checking issue after upgrade on Dell computer
http://support.microsoft.com/?scid=kb;en-us;310794

Does this ring a bell as well, as anything you might have done?

How to edit the registry offline using BartPE boot CD ?
http://windowsxp.mvps.org/peboot.htm

You can use the directions to Load, and modify the reg key specified using either a BartCD, or just slave the drive, and proceed with mounting the reg hive......

The keys they say remove do not exist in the HKEY_USERS hive, they are only in the HKEY_LOCAL_MACHINE hive. Could the location be in error on the KB artical?

Delete the following registry keys in the Windows registry:
HKEY_USERS\.DEFAULT\Software\Microsoft\Cryptography\Providers
HKEY_USERS\S-1-5-20\Software\Microsoft\Cryptography\Providers

That is boot from XP PRO cd to repair and run fixmbr?

That's correct.

I was using that KB article as a reference really, to see if you had performed either of the actions described....

I would load the reg hive back up, and look at the OOBETimer value, and modify it as suggested in the first post....