Computer won't boot - I'm stumped

[QUOTE=Rico]
Apparently whatever has taken control has locked the profile compaq_owner (which is the default profile) so nothing can access it. I’ve tried unhiding, setting attributes is DOS, deleting, a whole bunch of stuff and it’s impervious to opening.
[/QUOTE]

This is easy to overcome. With the drive mounted on your PC, browse to the \documents and settings directory, right-click the compaq_owner directory and select Properties then Security. Then click on the Advanced button. In there you want to Take Ownership of the directory and all its subdirectories. Then set the permissions such that a group called Everyone has Full Control. Then copy and delete.

One thing troubles me: you say this is the default profile? There should be a profile called Default User. It might be hidden.