SFC is the windows utility which checks for corrupt or missing system files.
When you're scanning, SFC asks for a disc you may not have - maybe it's an SP# disc, or a version which you just don't have on hand. Or if you have the disc it's still not accepting it.
First, get in the habit of ripping all software into a repository both at the customer's site and your collection. Do this for all software, including OS installation discs. This means using a tool to make an iso image of a disc. To rip discs I recommend poweriso or cdburner xp.
Secondly, know that you can mount an ISO from a \\tsshare - meaning if you choose to share your drives with a remote computer, you can browse to your ISO's and mount them for SFC.
To mount discs, I recommend Daemon Tools Lite -- NOTE: there is CRAPware bundled with the free version- be sure to read the prompts closely and hit SKIP during installation to avoid 'sweettoolbar' and other junk being installed.
As an alternative to installing software, you can copy the I386 folder from the installation CD to the root of C:\
IF you don't have the access to the disc at all, download it from your friendly, neighborhood pirate source! It's only illegal if you pirate the software, but you (hopefully) own the CDkey, so it's OK! You can even find the downloads hosted by reputable websites if you feel like putting your google skills to the test. Be wary though of tampered software. Usually you can find 'untouched' or 'original discs' . Also, be a dear and host your original ISO's for others to use!
In some cases, the SFC will not accept the disc you've entered even though it seems as though it should work. You need to make sure that the "SourcePath" location is the same as where the disc is mounted:
In the registry, browse to
Find the "SourcePath" key and change it from the original CD drive to either the drive letter of your VirtualDrive or if you copied the i386 folder to your C:\, then change to C:\
Reboot to reload the registry and then try running again.
If you run into an issue needing to be connected to console, read this article about the different switches for remote desktop. Basically, run>"mstsc /admin" to launch remote desktop in 'connect to console' mode.