How to Solve Microsoft Security Essentials Stopping by Itself

  1. Uninstall (Microsoft Security Essentials), should be able to remove MSE from Control Panel. Any problems uninstalling see: Uninstalling Microsoft Security Essentials  
  2. Recommend to restart the computer to ensure the uninstall is complete.
  3. Re-install the MSE. Can download a new MSE Installation File from:   http://windows.microsoft.com/en-us/windows/security-essentials-all-versions