The infected program might terminate abnormally, writing incorrect information into your documents. Or, the virus might alter the directory information on one of your system areas. This might prevent the partition from mounting, or you might not be able to launch one or more programs, or programs might not be able to locate the documents you want to open. Some of the more malignant viruses will erase your entire hard disk, or delete files. While some viruses are designed to be mere annoyances, others are programmed with the dangerous ability to damage files, destroy data and crash entire computer systems.
Viruses can be equally devastating to the home user.
If you notice any of the following symptoms on your home PC or portable computer, you may have a virus. It is not overstating the case to say that viruses could interrupt the free flow of information that has been built up by the personal computer in the last 10 years. Indeed, the prevalence of viruses has ushered in a new era of safe computing, to the point where those that ignore the guidelines run grave risks. The amount of lost time may be incalculable. As an indication of the severity of the problem, the federal government has helped to form a virus SWAT team called the Computer Emergency Response Team.