If you are having serious problems with your computer, the best course of action might be to reload the operating system and hardware drivers. This will enable your computer to recover from a boot sector virus or other serious infection. Reloading your operating system also can be effective if the operating system files have been corrupted or damaged.
Back up all of your user files, because reloading the operating system will destroy all of your data. You can use an external hard drive, thumb drive or an online backup service to save your files.
Insert the restore CD that came with your computer, then restart your PC. The computer will automatically boot and begin the restoration. You will be asked to confirm the reformatting of your hard drive during the process. The restore CD will not only reload the operating system but all of the hardware drivers as well. (If you do not have the restore CD, contact your computer's manufacturer.)
Insert the operating system CD if you do not have access to a restore CD. Shut down the computer and restart it. The computer will boot from the CD, and when the operating system menu is displayed, you will have the option to reload the operating system files. If you take this approach, you might also need to reload the drivers for your hardware by going to each manufacturer's website and downloading a driver for each device.