Cause

• The flashing lock symbol appears on your Dell laptop screen when you're trying to change a display setting that is not supported by the current resolution. It usually occurs when you're pressing keys that make changes to your display, such as function keys controlling the output to an external monitor.
  
  

Appearance

• The flashing lock symbol looks like a white padlock with blue horizontal stripes on a blue background. The padlock flashes from locked to unlocked. You cannot make changes to your display from your keyboard when the icon is flashing.
  
  

Resolution

• To get rid of the flashing symbol, click on your "Start" menu and select "Control Panel." Under "Appearance and Personalization," select "Adjust Screen Resolution." Click the arrow on the drop-down box to the right of "Resolution," and move the slider up or down to change the resolution. Click on "Apply," then "Keep."
  
  

Technical Support

• If you changed your screen resolution and the lock symbol won't go away, try shutting down your computer and rebooting it. If the problem persists, contact Dell technical support (support.dell.com). There may be a glitch in your system that would require Dell to repair or replace your laptop.