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Resolving and Preventing Viruses on Your Computer (Windows 7, Vista, XP)

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This document applies to HP and Compaq computers with Windows 7, Vista, and XP.
This document explains differences between viruses, helps in removing viruses, and offers suggestions for preventing future viruses.
CAUTION:Never open an attachment or a link in an email when you do not trust the sender. Sometimes a person intending to do harm sends an email message that appears to be from a trusted source, such as Microsoft. Most trusted companies do not attach software to email. If you do not trust an email, research it on the Internet or contact the company or sender named in the email.
NOTE:This document is not about spyware, adware or browser hijacking. Spyware might make the computer slow when connecting to the Internet and the computer might function as if it has a virus, but this is not discussed further in this document. For more information about spyware, adware or browser hijacking, see About Spyware, Adware, and Browser Hijacking Software .

Defining viruses, worms, hoaxes, Trojans, and security vulnerabilities

There are thousands of different viruses and damaging software programs that can harm your computer or make it perform slower. Typically, these software programs are the following:
  • Hoax - An email that usually states that it is harming the computer, but does not actually do what it says. Some hoaxes ask the reader of the email to perform a damaging process, such as deleting an important file. Most hoaxes are spread by people who do not know that the email is a hoax and who are hoping to alert others to a potential virus.
  • Phishing - Methods used to try to and move people browsing the Internet to a malicious Web site. When a person visits the Web site, the Internet browser tries to read malformed code on the page and induces a security hole or the Web page itself is designed to look similar to another popular Web page (to collect credit card or other personal information).
  • Security Vulnerability - A weakness in software that allows unwanted activity inside the operating system.
  • Trojan or Trojan Horse - A software program usually created to make a computer less secure. The software usually looks similar to a useful file that a person would want to open. The payload of a Trojan is usually delivered when the file opens and usually has devastating results. Trojans are often used to create back-doors (a program that allows outside access into a secure network). Trojans are most often delivered as an email attachment or through security vulnerabilities while browsing the Internet.
  • Virus - A software program that copies itself into another program, a hidden space on a drive, or items that support scripts. Most viruses copy only themselves, while a minority unleash a payload - actions caused by the virus. Payloads can damage files, deliver Trojan files, corrupt hard drives, display messages, or open other files. Typically, payloads deliver when a certain condition occurs, such as when the date on the computer reaches a particular day.
    A virus variant is a virus that has been altered to take advantage of the original virus code. By doing this, the virus variant is easier to create, creating more virus versions.
  • Worm - Another form of virus that finds vulnerable computers and copies itself to those systems. The most frequent methods of propagation are from email distribution lists, email signature scripts, and shared folders on the network. Worms might or might not have a damaging payload. The typical payload for a worm makes a computer more susceptible to other viruses and Trojans.

Instructions for resolving and preventing viruses

The steps in this section help you find, eliminate, and prevent viruses on a computer.
NOTE:If your computer has Windows XP or Windows Vista, and you think the computer might already have a virus, you can try Microsoft's Malicious Software Removal Tool (in English) to find and remove most common strains.
NOTE:When the computer is serviced or when a system recovery has been done, the computer software is changed back to its original configuration, meaning it is set to the same condition as when the computer was first purchased. All software and driver updates that were installed on the computer, from the time it was first started, are lost. In this like-new condition, the computer is more susceptible to viruses because the added security updates have also been removed. Perform the steps in this section after the computer returns from service or after running a system recovery.
NOTE:To fully protect a computer from virus attacks, install and use a firewall. Microsoft Windows 7, Vista, and XP have built-in firewalls. Many new HP and Compaq computers come with alternative Firewall software as well. Also, there are several firewall applications you can find by searching for them on the Internet.

Step 1: Obtaining Windows Security updates to help prevent viruses

Installing the latest critical updates from Microsoft makes a computer more secure. Regularly use Windows Update to help prevent the contraction of future viruses.
For more details on the latest vulnerabilities, review the following Microsoft Web page: Windows Security Bulletins (in English).
NOTE:Even if the latest critical updates were installed a week ago, check for updates again. Check for Windows updates on a consistent basis. Microsoft regularly provides critical updates to make Windows more secure. These updates are important for protecting a computer. If you have an always-on broadband connection, set the Window Update tool to automatically check for updates daily.
To use Windows Update, see Updating Drivers and Software with Windows Update for instructions. To make sure that the computer is free of viruses, continue through the remaining steps of this document.

Step 2: Checking to see if virus scanner software is installed correctly

Many HP and Compaq computers come with a trial version of antivirus software already installed, but you should check that it is set up and running correctly.
NOTE:Your computer might have come with a complementary 60-day subscription to Norton Internet Security. HP recommends following on-screen prompts to renew your subscription. Renewing your subscription not only helps protect your system against new threats, but can enhance Norton Internet Security with online protection that is faster, more responsive, and uses less memory.
Click the heading or the accompanying plus (+) sign to expand the information.
Check your computer for security software by clicking the system tray icon for security or accessing the security/action center from the Start menu.
  1. You can quickly determine if a computer has security software installed by moving the mouse pointer along the lower right corner of the Windows Desktop, over the icons next to the clock. A small text window displays over each icon. Read the text over each icon to find the tray icon for the security software. Right-click this icon to open the security software or examine more options.
    Figure 1: Tray icon for Norton Internet Security
    Tray icon for Norton Internet Security
  2. If you could not find a tray icon or you are still not sure if your computer has security software, do the following, depending on which version of Windows is running on the computer:
    • In Windows 7, click Start , type action center into the Search field, and press Enter to view the status of your security software.
    • In Windows Vista, click Start , type security center into the Search field, and press Enter to view the status of your security software.
    • In Windows XP SP2, click Start, click Control Panel, and then click Security Center to view the status of your security software.
    • For other versions of Windows, look through the Start menu to find security or antivirus software.
  3. If an antivirus software program is installed, skip to Step 4 . Otherwise, continue to the next step to install security software.

Step 3: Installing antivirus software

If antivirus software is not installed, HP recommends that you install antivirus software. New viruses are created and released often, and without antivirus software, the files and folders on the computer are at risk.
Computers with Windows 7 and Windows Vista come with Windows Defender. Most HP and Compaq computers come with free trial versions of antivirus software. These trial versions are usually limited versions that can be kept up-to-date for a specific period. After the period expires, your computer becomes more vulnerable to new viruses and security threats. Upgrade or refresh the subscription to keep virus definitions current and continue protecting your computer.
For example, Norton Internet Security provides some HP and Compaq computers with a free 60-day subscription to its virus protection service. You can download the latest virus information lists, called definitions, from Live update for 60 days. After that time, you can buy a subscription renewal from Symantec to safeguard the computer against the latest threats.
NOTE:If you have antivirus software installed, but want to install different antivirus software, make sure to remove the old antivirus software before installing new software. Doing so might prevent software conflict problems.
If you do not have any virus scanning software installed, you can use professionally developed products, such as Microsoft Security Essentials. This software is available from the Microsoft site, as a free download for all computers running Windows. For more information about Microsoft Security Essentials, see HP and Compaq Computers - Using Microsoft Security Essentials to Protect Against Viruses and Spyware .
To download the Microsoft software, go to Free Microsoft Security Essentials (in English).
To download the Symantec software, go to:

Step 4: Updating antivirus software definitions

Because new viruses are created and released often, regularly update the virus definition files for the antivirus software. A virus definition file is a list of known viruses that the antivirus software uses to find and eliminate viruses. Do the following to update the virus definitions:
  1. Open the antivirus software.
  2. Click buttons or menu items that read, update or live update.
  3. An update window opens. If the window does not open or if you cannot find the update feature, go to the antivirus software manufacturer Web site for more information. For a list of antivirus software support Web sites, see the Related support section.

Step 5: Scanning for viruses

After updating the virus definition files for the antivirus software, scan for viruses. Because each antivirus software has its own way of scanning for viruses, see the software manufacturer's Web site or help files if you need help scanning. Usually, you can scan for viruses by opening the antivirus software and clicking a scan button. For a list of antivirus software support Web sites, see the Related support section.
If you computer has Windows 7 or Windows Vista, you can scan for malicious software using Windows Defender. To do so, click Start , and type defender into the Search box, and then click Windows Defender. Click Scan.
Figure 2: Opening Windows Defender
Opening Windows Defender through the Search box
If a virus is found, the virus might have already damaged or destroyed some files on the computer. The antivirus software might or might not be able to repair the damage. If the software cannot repair the damage, the computer might need to be fully recovered. See Related support for antivirus software for information on performing a system recovery.
NOTE:If a virus was found and removed, open System Restore and delete any dates when the virus was active. This prevents the computer from accidentally becoming reinfected. See Related support for antivirus software for information on using Microsoft System Restore.

Windows vulnerabilities and security threats known by Microsoft

To keep aware of the latest Windows threats and vulnerabilities, see the Windows Security Bulletins from Microsoft (in English).
To see a list viruses and specific information about them, and to view information about protecting your computer from the viruses, go to Microsoft article - Computer viruses: description, prevention, recovery .

Related support for antivirus software

Security software support sites and other antivirus software (not HP)
Microsoft: Free Microsoft Security Essentials (in English)
Microsoft: Safety & Security Center (in English)
Check Point: ZoneAlarm Service and Support (in English)
Grisoft: AVG Anti-Virus (in English)
McAfee: McAfee Support site (in English)
Symantec: Symantec Support (in English)

HP Support forums

Find solutions and collaborate with others on the HP Support Forum
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