It simply replaces needed operating system files.(missing Dlls, etc.) It takes several minutes to accomplish its work, however. Perhaps as long as twenty minutes.
1. Click Start.
2. Click Run.
3. Type SFC /scannow in the run command slot. (Note: there is a space after SFC and that's a FORWARD slash in the middle, there.)
4. Press OK button below on run command menu box..
It will ask for your operating system disc/CD. Put it in your CD-ROM, and let it work.
This tweak appears harmless, and unlike some other tweaks, doesn't seem likely to challenge your system. It may help you when doing a spaced sequence of those things one does in order to 'cover your bases,' like chkdsk, ipconfig /flushdns, disk defragmenter, Disk properties file check with recovery of bad sectors, Comchec, DISKPERF -N, unchecking unneeded services in msconfig Start tab, etc.
This tip may not substitute for a full system repair, reinstall, update, or upgrade, however.