Simplest answer - use Windows Key & L
You'll need to have the password to open the locked screen.
Good advice from others though.
If your son's smart a re-start will allow him access to log on, you can stop this by disabling his account, start, run, lusrmgr.msc open users right click on his account choose properties and disable. Reverse this to enable, nothing will be lost etc.
CHeers Keith.
lol again back to my post
u can still reset the admin password or take it off
so if he's smart enough he will get back in
i know because i got into my secondary school computers a few years back and we couldn't do nothing
we couldn't even see the C: drive
but i noticed if u go through microsoft paint u can access it
so i copyed a short cut to cmd from C: to me file area
and from there ran a few things got into registry and deleted the admin password
got into computers loaded a few games onto network file server and put a few passwords and random files there 2
nearly got kicked out
and now at college its a very similar system but for the net they filter us through a hardware proxy
but they got more than 3
1 for students = restricted like hell
1 for staff = restricted like student but not as bad
1 dedicated for remote login / repair .etc and totally unrestricted
so i use firefox in rusian to change the proxy to default direct connect wich hooks me up with the dedicated connection
they disabled internet options from explorer
so its not that hard if u use google wisely
like i did...................lmao