I tested it and confimed with him that he did use Iseeuu's method. While I was aware of the recovery console. I had not known that it was accessable through the advanced boot menu. I had thought that the recovery console is only accessable through a recovery CD, which is why i ruled it out as an option when I had said he did not use any peripheral devices such as USB or CD to boot from to get an OS loaded from.
Thank you to everyone for your help
We are glad you solved the mystery! Can I assume then, that giving the Default Administrator Account a password will prevent him from using recovery console to access your computer in the future?
If I may, I would like to share my philosophy on computer security, it is much like my home security. My front and back doors are closed and locked but only a small metal "strike plate" stands between a large person and the interior. It wouldn't take much force to shred the door frame and 2X4s around the door. Likewise the windows are easily broken with a rock giving easy access. I do not have an electric door opener so there is no security risk there. To have a really secure home, I would have to remove all openings, doors and windows, and live in a sealed box. Who wants to do that? Who can live like that? Instead I use all reasonable measures to make it easier for a thief to go somewhere else, easier targets where the doors are left unlocked or open.
Some basic computer security measures discussed on this forum are:
To use a "Limited User Account" for everyday and an "Administrator Account" for management and password protect all accounts including the "Default Administrator Account".
Use the password feature when your computer comes out of sleep or hibernation, or after the screen saver.
Use a strong password, like you mentioned, alpha-numeric. It takes about 20 seconds to crack a password of all lower case letters. Adding a capital letter makes it 26 times harder to crack. Adding a number and a special character takes so long to finally crack, it is just easier to move on. As an example, I like to take a familiar word: administrator, spell it backwards and add numbers: R08tsinimda.
Set the hard drive as first boot device and password protect the BIOS.
Use anti-virus / anti-spy software to detect trojans, keyloggers, and other malware.
Never open an email-attachment from an unknown sender (and sometimes from known senders).
Of course, just as someone can break open the door to my home, if they get physical access to my computer they can delete the BIOS passwords and gain access. There is no reasonable security measure to prevent that. But why would they expend that much effort, take that kind of risk, when there are so many easy targets?
Cheers!
Robert