“System File Checker?” You possibly repeat, inquisitively.

“Wasn’t that something in Windows 98?”

Yes it was; and I’m not encouraging you to use Windows 98 either. (Far from it: Windows 98 is now a significant security risk.) It still exists in Windows XP, and even in Windows Vista too.

“It is? I’ve never seen it in XP or Vista…”

Oh it’s there; ‘just that Microsoft buried it deep in the operating system.

We’ll talk about how to get it going in a while. First I wanted to explain a little bit about it:

There are certain files in Windows that are critical components of the operating system. If they weren’t there or they became corrupted, (As they might do from time to time.) then Windows doesn’t function properly; usually with the result that it crashes with a BSOD. These files are known as ‘protected’ files, and are hidden by default from all users. (They’re easy-peasy to unhide; but that’s for a different article perhaps.) At times if you inadvertently attempt to replace one of the protected system files; by installing crappy software maybe, or accidental deletion, Windows may respond with an “Are you sure you want to do that? You’re attempting to replace a protected system file.” type-message, and/or will put the original file back in place afterwards on some occasions.

- But as I said; these files can get corrupted; causing Windows to behave strangely, to malfunction, and even crash in a resultant blue-screen. Also – And even I’ve done it in the past; so there’s no need to feel ashamed of it – if you click ‘Yes’ when Windows asks ‘Are you sure you want to do that? You’re replacing a protected system file…’ – Because you’ve just paid for the piece of software you’re installing, so there’s surely nothing wrong with it or harmful to your computer. – and a protected system file gets replaced with one that’s almost identical, but probably has spyware in it too: Windows doesn’t always notice the difference at first, if it’s well coded.

System File Checker reads the digital signatures of all the protected files and checks their parity. If it finds something not quite right it replaces the file with a new copy. System File Checker will use the on-disk i386/cache if possible; but it prefers to take the relevant files straight from the installation disk if it can; and in some cases it might have no alternative anyway.

How to start System File Checker:

In Windows 98 you just clicked on a sub-menu item on the start menu.

– But in XP it’s easier to do it from a command-prompt. Click Start and type sfc /scannow.

In Vista; according to  Microsoft Help and Support: -

Type the following command, and then press ENTER:

sfc /scannow

 

If you don’t have an installation disk but you need to run the System File Checker, and the System File Checker asks you for the installation disk, don’t panic. There should be a partial disk-image on your C: drive containing all the files you need. It’s called i386. There are probably several; but the one we’re looking for here has close to 7,000 files in it and contains the files winnt.exe and winnt32.exe. (You won’t actually need these files for System File Checker; but if you find them in the i386 directory then you’re looking at the right one.)(C:\Windows\ServicePackFiles may be a good location to start looking for it.)

When the System File Checker tells you to insert the installation disk, just click OK. It’ll bring up a dialog box asking you to provide the location of the installation disk. Just browse to the i386 folder you’ve located or type in the path to it.

Not only will Windows use that directory at the time; but it’ll also remember it and it’ll be the first place it looks in a similar situation. ‘Handy eh? – Especially if your installation disk has been chewed up by the dog or accidentally used as a coaster when you forgot to put it away safely.

It doesn’t say this in any Microsoft documentation; but I’ve heard it from MVPs and others in the know, and I agree that it’s a good idea: After running SFC; reboot. It’ll set any file replacements in stone as it were.

There’s more on SFC in more detail here at Microsoft’s knowledgebase; so if you think I’ve missed something out; click this link for Windows XP and Server 2003, or this link for Windows Vista.

And that’s yer lot. Please comment.

You what? – You want pictures with it too? Do you want me to come over and run the thing for you too? Jeez!

Scroll down…

            

Here:

‘Satisfied?