Using SFC (System File Checker)/Scannow

System files can sometimes get written over or deleted.  SFC (System File Checker) scans your Windows XP system and replaces the missing files.  Missing system files can cause startup/boot problems or other operating system headaches.  SFC is part of the WFP (Windows File Protection) feature that prevents programs from writing over critical system files.

I was once working on a computer that was having a startup problem, ran the command line utility SFC /scannow, and voila!  Problem fixed.  SFC scans the system and determines if there are any missing files.  If so, the files are obtained from cache (%systemroot%\system32\dllcache).  If not in cache, SFC will obtain the files from the installation source on the network or the Windows CD-ROM.  You might be asked to insert the Windows Installation CD-ROM.

To use the SFC utility:

1. Go to Start;All Programs;Accessories;Command Prompt
2. Type SFC /scannow and press Enter (there is a space after SFC)
3. If prompted, insert your Windows XP Installation CD-ROM.
4. Wait until command finishes and your files are verified.