There are generally two administrator accounts. One in the normal windows environment and the other in Safe mode. If you have'nt protected that angle he could be using that to enter the Administrator setup.
Also create a plain "Limited account" for his usuage not any power user etc.
Hope this help
My son (bless him) was up all hours on the computer so I decided to set myself up as an administrator in user accounts and have a password to log onto the computer. That way when i switched it off he wouldn`t be able to use it as he wouldn`t know the password.
Whilst the computer was on he also set himself up as an administrator-which i`ve now deleted.
How can I stop him from doing this again?
Can I somehow password protect the user account.
I thought that as an administrator you could prevent anyone from doing this.