Scan and Fix Your Hard Drive: Windows System Files

Run the Windows file checker

All activities, including applications such as word processors, email clients, and internet browsers, are controlled by system program files. Over time, the files can be changed or corrupted by new software installations, viruses, or problems with the hard drive. Scanning and fixing Windows system files improves the function and speed of your computer.

Instructions in this article apply to Windows 10, Windows 8, Windows 7, and Windows Vista.

Why Run System File Checker

The more corrupt the system files are, the more unstable and problematic the Windows operating system will become. Windows may crash or behave differently than you expect. That is why scanning and fixing Windows system files is important.

The System File Checker program scans all protected system files and replaces corrupted or incorrect versions with the correct Microsoft versions. This procedure can be beneficial, especially if your computer displays error messages or runs erratically.

Run System File Checker in Windows 10, 7, and Vista

To use the System File Checker in Windows 10, Windows 7, or Windows Vista, follow these steps:

  1. Close any open programs on the desktop.

  2. Select Start.

  3. Enter Command Prompt in the Search box.

  4. Select Run as administer.

    Command Prompt in Windows 10 with Run as administrator highlighted
  5. Enter an administrator password, if requested to do so, or select Allow.

  6. At the Command Prompt, enter SFC /SCANNOW.

    Administrator Command Prompt
  7. Press Enter to begin the scan of all protected system files.

    System File Checker scan in process
  8. Do not close the Command Prompt window until the scan is 100% complete.

Run System File Checker in Windows 8.1 and 8

To use the System File Check program in Windows 8.1 or Windows 8, follow these steps:

  1. Close any open programs on the desktop. 

  2. Point to the lower-right corner of the screen, and select Search, or swipe from the right edge of the screen, and select Search.

  3. Enter Command Prompt in the Search box.

  4. Right-click Command Prompt, and select Run as administrator.

  5. Enter an administrator password, if requested to do so, or select Allow.

  6. At the Command Prompt, enter SFC /SCANNOW.

  7. Press Enter to begin the scan of all protected system files.

  8. Do not close the Command Prompt window until the scan is 100% complete.

Allow System File Checker to Work

It may take from 30 minutes to a couple of hours for the System File Checker to scan and fix the Windows system files. It works fastest if you don't use the computer during this process. If you continue to use the PC, performance will be slow.

When the scan is complete, you will likely receive one of the following messages:

  • Windows Resource Protection did not find any integrity violations. The computer isn't missing any files or doesn't have any corrupted system files.
  • Windows Resource Protection found corrupt files and successfully repaired them.
  • Windows Resource Protection could not perform the requested operation. Restart the computer in safe mode and confirm that the Pending Renames and Pending Deletes folders are under %WinDir%\WinSxS\Temp.
  • Windows Resource Protection found corrupt files but was unable to fix some of them. Corrupted files must be repaired manually.