Accounts Locked Out

I am having some problems with Windows XP machines – after running MS Updates (unsure of which one affected machines) – all accounts seem to be locked out.

It had locked everything out from Recovery Console to Safe Mode. I tried using Linux boot disk to change password, which will only work with Recovery Console which is no good as I don’t want to have to rebuild our machines.

Would anyone have any idea of how to reset accounts or how to create a new account that would possible let you access machines.

Many thanks