Symptoms

Please note that your computer may behave strangely and NOT be suffering from a virus or spyware problem. Other problems include hardware failure or something you did to change the setup of the computer.

However, if you suspect an infection, it is better to diagnose it than ignore it.

Increasingly viruses and spyware are being designed for stealth and do not advertise their presence at all. A positive scan is the only way of being sure whether or not you have an infection.

The symptoms of a virus infection and a spyware problem overlap. Sometimes spyware and viruses work together so you need to check for and eliminate both.

Signs of a virus infection:

• You get a virus warning from antivirus programs you have installed.
• Your computer or internet connection has slowed down.
• Your computer starts behaving strangely or crashes frequently.
• The virus actually announces itself.
• You double-clicked on an email attachment and odd things started happening.
• An antivirus program is disabled for no reason and it cannot be restarted.
• An antivirus program cannot be installed on the computer or it will not run.
• Strange dialog boxes or message boxes appear onscreen.
• You get an email from someone else saying that you sent them a virus.
• New icons appear on the desktop.
• Strange sounds or music plays from the speakers unexpectedly.
• A program disappears from the computer, but you did not intentionally remove it.
• Windows will not start at all or displays error messages while starting up.
• You receive out-of-memory error messages even though your computer has plenty of memory.
• New programs do not install correctly.
• A disk utility such as Scandisk reports multiple serious disk errors.
• Your computer always stops responding when you try to use Microsoft Office products.
• You cannot start Windows Task Manager (pressing CTRL-SHIFT-ESC will normally start it).
• However, because many viruses are written for criminal purposes, they are increasingly designed for stealth and may present no symptoms at all.

Signs of a spyware problem:

• You get a warning from anti-spyware programs you have installed.
• Computer has slowed down.
• Internet connection has slowed down.
• Your web browser home page has changed.
• You get lots of pop-up adverts.
• There are new toolbars in your browser.
• There are new icons on your desktop.
• You can’t get to certain websites.
• Some spyware will not advertise its presence and only a scan will discover it.

Beware of virus hoaxes

Sometimes people receive an email purporting to inform them about a security risk. If you are concerned because of an email you have received, check to see if it is a hoax before acting on it. Several websites contain directories of hoax emails, including:

• F-Secure.
• McAfee.
• Microsoft's Malware Protection Centre Encyclopaedia.

Warnings

• It is important to take immediate action to remove viruses and spyware and to stop them coming back. The consequences of inaction are serious (see What’s the worst that can happen?).
• Removing viruses and spyware completely can be time-consuming and require a degree of technical expertise. On the other hand, ill-considered panic measures can cause more damage than a virus. Don’t panic.
• There is no guarantee that a virus or spyware can be completely removed, although it is usually possible in most cases.
• Some viruses and spyware block access to security websites or disable security defences which can complicate removal.
• We recommend that you get help if you need it (see Get technical support).

Immediate action

• Do not click on pop-up windows that offer free anti-virus or anti-spyware removal. These may be triggered by the infection itself.
• If you have access to IT support, for example at work, contact them immediately.
• If you are going to get someone else to help you, it is probably best to switch off your computer and stop using it until they arrive.
• Some of the following measures require internet access, but if you are not using the internet and have to leave the computer on, disconnect the internet connection.
• Backup your data (see Make regular backups).
• If you have anti-virus software, download up-to-date anti-virus signatures and perform a complete system scan. You should get further advice on removing specific infections when the scan is complete or from the website of the company that developed the software.
• If you do not have anti-virus software installed or you think it is not working or up-to-date, run a free online scan for viruses. Many of the major security software firms have free online applications that will scan your computer for viruses and determine if you are infected. Two free online scanners can be found at: McAfee and Symantec.  These will give you guidance on how to remove the specific viruses and, for common viruses, they will direct you to online removal tools.
• Run a free online scan for Spyware. Some software companies provide this tool on their website:
  • Webroot.
  • Zone Labs.

Removing spyware

There are a number of effective spyware scanning and removal programs. Some are free, while most offer a limited-time trial version. Options include:

• Microsoft’s Windows Defender.
• Spyware Blaster.
• Spy Sweeper.
• Spybot Search and Destroy.
• AdAware.

Removing Viruses

Removing a virus isn’t always as simple as deleting a file. They can attack different parts of your computer operating system and really get their foot in the door.

If you already have anti-virus software on your computer, follow its instructions to remove any detected viruses.

There are free removal tools for many common viruses online at the following sites:

• Symantec.
• Microsoft.

If the virus on your computer is covered by these tools, go ahead and remove it. For viruses that aren’t covered by these tools, you’ll need to get an anti-virus program (see Install anti-virus software) and use the developer’s website to get detailed removal instructions.

If the virus in question interferes with the installation of anti-virus software, follow the specific instructions on the website to stop it doing so.

Install your chosen anti-virus software, run a full system scan and follow instructions to remove any remaining viruses.

Rebuild your defences

To ensure that you stay protected, at the very least you need to:

• Install anti-virus software
• Stop spyware
• Use a firewall
• Get the latest Windows updates

Protect your privacy

Because a virus or spyware attack can give criminals access to your personal information and passwords, you need to take steps to protect your privacy after clearing up an attack.

• Change passwords for your computer and online services, especially any that have access to your bank or credit card information.
• Use strong passwords.
• Monitor bank and credit card statements for unusual transactions.
• Watch for others signs of identity theft (see Undo identity theft).