windows7rc_bloglogo Effective February 15, 2010, the expiration notification process begins:
  • Windows 7 RC users receive an expiration notification in the task bar one time per day.
  • Windows 7 RC users are presented with the Notification Wizard one time every four hours and then one time every hour.
Effective March 1, 2010, Windows 7 RC enters the next phase of expiration:
  • Expiration notifications in the task bar continue.
  • Computers that are running Windows 7 RC restart every two hours.
    Important When the computer restarts, your work will not be saved.
Effective June 1, 2010, Windows 7 RC expires:
  • Windows starts to a black desktop.
  • Windows 7 RC users are presented with a Windows Activation screen. The screen states that the Windows that you are running is not genuine.
  • Computers that are running Windows 7 RC restart every two hours.

See http://support.microsoft.com/kb/971767 for more information.