What are critical system files?

Published: April 26, 2010

Updated: March 30, 2011

Applies To: Windows Home Server 2011

When you install the Windows operating system, the Setup program creates folders on your system drive where it places files that the system requires to start and run. Critical system files include files with .dll, .exe, .ocx, and .sys file extensions. Some of these files True Type fonts. In addition, system state files, such as the system’s registry, are required for the operating system to run properly.