The easiest way to boot in to safe mode is pressing the F8 button before Windows 7 starts to boot.But it may not always work or you may need enable or disable advanced settings for the Safe mode.
As the tutorial is intended for advanced users, we are not presenting screenshot on every step.
You can schedule Windows 7 to start in safe mode from the System Configuration Utility. To do this, click Start > type “msconfig” (without quotes) in the search field and run it as Administrator. Go to Boot tab, and select “Safe boot” from boot options:
You can select to safe boot Minimal, Alternate Shell, Active Directory repair or from Network. Click Apply and OK and then restart Windows 7.