If some Windows functions aren't working or Windows crashes, use the System File Checker to scan Windows and restore your files. Though the steps below might look complicated at first glance, just follow them in order, step-by-step, and we’ll try to get you back on track. Run the System File Checker tool (SFC.exe)

The Program Install and Uninstall troubleshooter helps you automatically repair issues when you're blocked from installing or removing programs. It also fixes corrupted registry keys. First, you'll need to download the troubleshooter. Download troubleshooter.

Follow these steps to automatically diagnose and repair Windows security problems by turning on UAC, DEP protection, Windows Firewall, and other Windows security options and features. Select the Download button on this page.

System File Checker is a utility in Windows that checks for problems with files on your computer. To run it, follow these steps: Make sure you've installed the latest updates for Windows, and then restart your machine. To find out more, read Update Windows.

Resolution. This issue can be resolved and the PC Repair virus removed by running the Microsoft Safety Scanner. To do this, follow the steps below: Go to http://www.microsoft.com/security/scanner/en-us/default.aspx and click the Download Now button.

The Program Install and Uninstall troubleshooter helps you automatically repair issues when you're blocked from installing or removing programs. It also fixes corrupted registry keys. First, you'll need to download the troubleshooter. Download troubleshooter.

When you start your computer successfully, the Windows Registry Checker tool (Scanreg.exe) creates a backup of system files and registry configuration information (including user account information, protocol bindings, software program settings, and user preferences) once daily.

User Account Control (UAC) is designed to prevent unauthorized changes to Windows. When an action requires administrator-level permissions, UAC prompts you to approve or deny the change. This helps protect your Windows device from malicious software and unauthorized modifications.

Regsvr32 is a command-line utility to register and unregister OLE controls, such as DLLs and ActiveX controls in the Windows Registry. Regsvr32.exe is installed in the %systemroot%\System32 folder in Windows XP and later versions of Windows.

In Windows 10, the new action center is where you'll find app notifications and quick actions. On the taskbar, look for the action center icon. The old action center is still here; it's been renamed Security and Maintenance, and it's still where you go to change your security settings.