There are numerous ways to fix corrupted system files in Windows XP like:
Starting the computer by selecting CD/DVD drive option as first boot sequence in BIOS. Insert operating system CD/DVD into CD/DVD drive and select “ R” option to repair corrupted files during the Windows XP operating system installation.
If the operating system is already installed, then boot the operating system and insert operating system CD/DVD into CD/DVD drive. Click on START Windows XP installation and select UPGRADE instead of FULL INSTALLATION option and click NEXT to continue operating system installation. If FULL INSTALLATION option is selected then all existing user files and folders including operating system files and folders will be deleted. The option FULL INSTALLATION is considered as new installation of operating system.
The easiest way to repair corrupted files is to boot the already installed Windows XP operating system. First insert operating system CD/DVD into CD/DVD drive then hold the WINDOWS key and press R to open RUN window or go to START and click on RUN to open RUN window. Type " SFC /SCANNOW " without double quotes and press ENTER key to fix all corrupted files on Windows XP. SFC (SYSTEM FILE CHECKER) is a DOS command utility to check and repair system related files. There are many parameters that can be used with SFC command. For more parameters hold WINDOWS key and press R to open RUN window. Type " cmd " without double quotes and press ENTER key to open DOS window. At the command prompt type " SFC /? " without double quotes and press ENTER key.
Note: Always use original operating system CD/DVD for good and better performance. With original operating system installed, you will have many featured enabled like WINDOWS UPDATES thus making your computer fully secure from software bugs.