How to run the SFC when offline. "The System File Checker (sfc.exe) is an useful tool that lets you scan the integrity of Windows system files, and repair corrupt or missing system files. Numerous cases have been resolved thus far by running Sfc.exe with the "scannow" parameter. However, there are situations where in a corrupt or missing system file prevents Windows from booting normally, and running Sfc.exe from Windows isn’t possible. In such cases, Sfc.exe can be run offline using two additional parameters, via the Windows Recovery Environment (Windows RE) in Windows 7 and Windows Vista."