Microsoft Safety Scanner

How do I find and remove a virus?

If you can answer "yes" to any of the following questions, your computer might have a virus.
Is your computer running very slowly? A common symptom of a virus is much slower than normal computer performance. 

However, there can be other reasons for slow performance, including a hard disk that needs defragmenting, a computer that needs more memory (RAM), or the existence of spyware or adware. For more information about spyware, see How to tell if your computer is infected with spyware.

Are you getting unexpected messages, or are programs starting automatically? Some viruses can cause damage to Windows or some of your programs. The results of this damage might include messages appearing unexpectedly, programs starting or closing automatically, or Windows shutting down suddenly.

Is your modem or hard disk working overtime? An e mail virus works by sending many copies of itself by email. One indicator of this is that the activity light on your broadband or external modem is constantly lit; another is the sound of your computer's hard disk continually working. These are not always symptoms of a computer virus, but when combined with other problems, can indicate a virus infection.

To check for viruses, scan your computer with an antivirus program. New viruses appear every day, so keeping your antivirus program updated is important. For more information about computer security. To learn how to remove malicious software (malware) from your computer, Download Microsoft Security Scanner 

A fast way to check whether your PC has a virus is to use Windows Defender. This malware protection is included with Windows and helps identify and remove viruses, spyware, and other malicious software.

If you're using Windows RT 8.1, Windows Defender is always on and can't be turned off.

Scan your PC with Windows Defender

1. Open Windows Defender by swiping in from the right edge of the screen, and then tapping Search (or if you're using a mouse, pointing to the upper-right corner of the screen, moving the mouse pointer down, and then clicking Search), entering defender in the search box, and then tapping or clicking Windows Defender.
2. Under Scan options, pick the type of scan you want to run:
• A Quick scan checks only the areas on your PC that malicious software is most likely to infect, and any apps currently running.
• A Full scan checks all the files on your PC. Depending on your PC, this scan might take an hour or more.
• A Custom scan checks only the files and locations that you choose.
3. Tap or click Scan now.

Remove a virus manually

Windows Defender will typically remove viruses automatically. However, in some cases you might need to remove a virus manually. This can be a technical process that you should try only if you've exhausted all other options, you're familiar with the Windows registry, and you know how to view and delete system and program files in Windows.

1. First, run your antimalware app to identify the virus by name. If you don't have an antimalware app or if your app doesn't detect the virus, you might still be able to identify it by looking for clues about how it behaves.
2. Write down the words in any messages it displays, or, if you received the virus in email, write down the subject line or name of the file attached to the message.
3. Then search an antivirus provider's website or the Microsoft Malware Protection Center for references to what you wrote down or to try and find the name of the virus and instructions for how to remove it.

After the virus is removed, you might need to reinstall some software or restore lost info. Making regular backups of your files can help you avoid data loss if your PC gets infected again. If you haven't made backups in the past, it's a good idea to start now. For more info, see Restore files or folders using File History.

How do I uninstall antivirus or antispyware programs?

If you use more than one antivirus or antispyware program at the same time, your PC may experience decreased performance, become unstable, or restart unexpectedly. Before you install Microsoft Security Essentials, or if you want to resolve issues with Microsoft Security Essentials, including installation issues, you must first completely remove any Internet security programs from your PC.

1. In Windows 7, click Start. In the Search programs and files box, type appwiz.cpl, and then press Enter.
2. In the list of installed programs, uninstall any other Internet security programs.
3. Restart your PC.

Note

• Some Internet security apps don’t uninstall completely. You may need to download and run a cleanup utility for your previous security app for it to be completely removed.
• If you use another antispyware program together with Microsoft Security Essentials, we recommend that you turn off real-time scanning in the other program. For more information, see the documentation supplied by that antispyware program.

Important

• If your antivirus program is disabled, or if you don't have one installed, you should follow these guidelines:
• Don’t download or open files from sources that you don't trust.
• Don’t visit websites that you don't trust.
• Don’t open email attachments from contacts that you don’t trust.