Have Win 7 Spanish edition. Screen blanks out after no activity for 10 minutes. When I move the mouse to bring it back, I get 2 boxes. 1st box in center says: English-(name) Blocked. 2nd box below center says: Change user. So, I click on the 2nd box and get another screen with a box in the center that says in Spanish "Con Session Iniciada (Inicial session)? Well, how do I get rid of the 2nd box on the first screen? It wasn´t there when I first got Win 7. Don´t know how it came to be there.
If you can get in initially but it locks later, here are the instructions to correct this
If not restart and tap the f8 key every couple seconds until you get a menu with safe mode as an option, select safe mode.
You should have an account called administrator that comes up, if so select it and try to apply the same fix from that account.
Good luck 
I still have the problem, but I just extended the time for blanking out the screen. Now, I never have the problem.