Boot into Safe Mode
1. Save your work, and restart the computer.
2. Press and hold down the 'F8' key as your computer is starting back up. Release the 'F8' key when you reach the 'Advanced Boot Options' menu screen.

3. Use the 'Arrow' keys to select 'Safe Mode with Command Prompt,' and then press 'Enter.' This loads Windows in Command Prompt mode.
Repair the Host File and Any Other Damaged Files
4. Insert the Windows disc into your computer.
5. Type 'Takeown /f Rundll32.exe' and press 'Enter.'
6. Type 'icacls Rundll32.exe /grant administrators:F' and press 'Enter.' This command grants you full control over the host file.
7. Type 'Rename 'Rundll32.exe Rundll32.Bak' and press 'Enter.' This creates a backup of the host file while simultaneously removing the executable from the system directory. This allows your repair utility to detect that it is missing and ensures it is rebuilt.
8. Type 'SFC /Scanfile=C:\Windows\System32\Rundll32.exe' and press 'Enter.' This launches a System File Check. The utility determines the file is missing and rebuilds a clean copy.
9. Type 'SFC /Scannow' and press 'Enter.' This will scan all system files and repair or replace any damaged ones. Wait until the utility has notified you of completion.
10. Remove the Windows disc from your drive. Type 'Exit' and press 'Enter' to restart Windows.