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.

If you cannot boot your computer, contact your campus Support Center. Otherwise, you can try to address the problem with security software.

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 (called the 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 drive.

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 normal.dot). 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 Go and then Go to Folder.... In the field, type ~/Library/Application Support/Microsoft/Office/User Templates, and then click Go.) 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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