System File Checker to check for modified Windows files. System File Checker (SFC) is a Windows utility that can be used to scan for and restore corrupt Windows system files. SFC can be used to detect and fix any modified or corrupted system files on a computer, and thus should be checked first when a user reports that their computer has been running slowly since the installation of security applications [1][2]. By checking SFC, any modified or corrupted system files can be identified and fixed, potentially improving the overall performance of the computer.