What should I do if my computer has a virus?
Note: For a list of resources to help you find information about particular viruses, see What are viruses, worms, and Trojan horses?
Don't panic if your computer seems to have a virus. Common software problems, such as program execution errors and corrupted files, can create symptoms that appear to be virus-related, so it's important to distinguish between virus symptoms and those that come from corrupted system files. You should also rule out more typical causes (e.g., having recently installed new software) before suspecting a virus.
However, if your computer begins to act strangely or behaves differently than it has in the past, it may be infected with a virus. Symptoms such as longer-than-normal program load times, unpredictable program behavior, inexplicable changes in file sizes, inability to boot, strange graphics appearing on your screen, or unusual sounds may indicate a virus on your system.
Note: For personal computers, UITS recommends Windows Defender for Windows 8.x, which comes as part of Windows 8.x as a full antivirus suite. For Windows 7 and Vista, UITS recommends Microsoft Security Essentials, available free of charge via IUware. Be sure to have only one antivirus program installed.
If your antivirus software finds a virus, it will give you the option
to repair, delete, or quarantine the infected file. The quarantine
option simply copies the infected file to an isolated directory
quarantine folder) on your hard drive, which
protects it from access by users or other files. Also, if your
antivirus software can't repair an infected file (e.g., if the damage
is too extensive, or results from an unknown virus), it copies the
file into the
quarantine folder and deletes it from the
If you have had infected files, you may need to do additional repair work after your virus software has cleaned them. The easiest solution is to open the cleaned file, select all the information in the document, and copy and paste it into a new document.
Note: Files that have been cleaned can often appear to have some file corruption remaining after removal of the virus and macros. If garbage or unwanted words have been introduced into your files, you may be able to use the search and replace function of your word processing or spreadsheet application to eliminate them.
If the infected file was a Microsoft Word file, as a final step you
can delete the
normal.dotm file (in pre-2007 versions of
Office for Windows, the filename will be
This file's location varies depending on how Word was installed; use
the respective search features of Windows or Mac OS X to locate the
proper file. (On a Mac, you can also find the file in the Finder by
selecting and then . In the
Templates, and then click .) Delete the
normal.dotm file; the next time you open Word, it will
automatically recreate a correct version of this file.
Note: With certain system-level infections, antivirus software cannot entirely remove or repair viral problems and cannot account for changes that may have been made during the infection. In these cases, you will need to perform a clean installation of the operating system. For more, see In Windows, how do I safely rebuild my computer?
This is document cact in the Knowledge Base.
Last modified on 2013-11-18.
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