Computer viruses are programs that can reproduce in a computer without the consent of the user. The term virus is commonly used interchangeably with adware or spyware. However, only viruses have the capability to multiply. A virus, other than simply annoying, can cause serious problems to your computer. These include running out of memory, slow processing, data loss and damage (software only, not hardware).

            A computer can be infected through portable storage devices (external hard disk, USB thumb drives, CDs and diskettes). Connection to the internet or a network also increases the risk of infection.

            Usually, codes are attached by computer viruses to program executables. If the user, or the OS, runs the executable, the virus reproduces itself.

            Reformatting or reinstalling the OS is the best way to clear the virus from a PC. Otherwise, it is not totally safe to use it. However, there are antivirus programs and software that can search and delete the malware. There are also easy steps that may work in restoring your PC—even without the help of experts.

System Restore
It is very annoying that certain computer viruses can disable important OS tools. As for Windows, viruses like Ciadoor can disable the command prompt and the task manager. Users will usually get the notification, “Disabled by the administrator,” even if they have not done anything.
However, this can easily be solved by rebooting the computer. Start the computer again in “Safe Mode.” Then, you will be able to use the “System Tools.”

Another way is to use “System Restore.” It is a tool that comes with the Windows OS, starting with Windows ME to Windows 7. When executed, it will restore the registry to a previously saved checkpoint—given that the computer is still uninfected on or before the checkpoint date.

Antivirus Protection and OS Updates
            You may use web-based virus scanning tools. Some sites allow detecting and cleaning of

computer viruses online. However, their features are limited. Their primary intention is to advertise their antivirus software.
            It is advisable to purchase a licensed antivirus program. Look for one that is affordable and reliable. Read reviews. A licensed antivirus will allow regular download of updates and virus definitions. After all, hundreds of new viruses are being released every day.

            Antivirus software can be used to scan the system, including hard disks and portable devices. They can automatically detect infected files, and suspicious installations. Then, the user can delete or quarantine the infected files.

It is also smart to update your OS regularly. New security tools are being released frequently, including registry defenses. New Operating Systems ask users if they will allow installations and registry changes. This can help in avoiding automated installation and file duplication.

Reinstalling the OS
            The safest and surest method is to reinstall the OS in the hard disk partition. Make sure that you use a clean bootable disc. This is more efficient than letting your antivirus do the job. After the OS, you can now reinstall all your programs—each fresh and malware-free.

            If the virus does not allow reinstallation on your own PC, you can plug the hard disk to another computer. Then, you can reformat it there. Just be careful not to run any executable from the drive as it may infect a new host.