Can I run more than one antivirus program?

Carole asks:

Is it OK to run Windows Defender with Norton or McAfee antivirus protection?

You should never run more than one antivirus program at the same time. The two programs could slow down your computer, and they might even identify each other as a virus, which could lead to file corruption or other conflicts and errors that make your antivirus protection less effective—or not effective at all.

We recommend that you use the antivirus protection that’s included in your version of Windows. Windows 8 includes antivirus and antispyware protection called Windows Defender. If you use Windows 7 or Windows Vista, you can download Microsoft Security Essentials at no cost.

For more information, see How to boost your malware defense and protect your PC.

About the Author
Eve Blakemore

Group Manager, Trustworthy Computing

Eve Blakemore is a Group Manager for Trustworthy Computing who delivers consumer guidance around the latest trends in security and privacy. Eve joined Microsoft in 1998 and has worked in corporate and field roles with Microsoft Learning, US Public Sector, Read more »

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  1. Anonymous

    Since MS can not provide a call number to call to talk to a real person, would it be possible to unlock everyone's account that was temporary block for two weeks after first sign in? This will let me get my emails to be printed out so that I have a record off them and than if MS wants my account than they can have it. I just want my emails if possible. I think I have about 200 emails that I would need to print out so two weeks should be fine for me. Plus would send email to my friends and family to let them know that my email was taken by MS.
    Please help me.

  2. Anonymous

    I fell for a scam from an outfit that claimed to be Microsoft trained experts for a free check of my computer which  then claimed to have found and removed a number of problems but would need payment for removing some remaining items.

    This  resulted in my getting a blue screen from a  rootkit MBR MAYACHOK ok B (boot image)  which was discovered by the Secure IT antivirus program which was on my computer but they said after trying for  some time and resetting the system to an earlier time without it  removing the virus that they would recommend wiping the hard drive and reinstalling Windows 7 which would take off all the pictures and files etc. on my computer.  

    I have been unable to use my computer except by starting it in safe mode w/networking for two weeks after getting the first blue screen. I seem to not have email or online access by programs etc.

    Would I be able to download Security Essentials and would it help now ?  I would appreciate your advice.  

                                                                                                                                                                      Thanks ,  Bob  

  3. Anonymous

    It is possible to run two AV products at the same time.  It works better if they do not scan the same way–say pair a true AV product with an antimalware product.  It is best to exclude each AVs program folder, data folder, and quarantine/signature folders (if they are not in the program folder), and the temp folder created during scans, from the other AV to prevent conflicts.  There will be some overlap in which they may scan the same file, but the overlap should not be for a long enough period of time to really consume excessive resources.  In the event there is significant overlap, you should disable the real-time scan capability of one AV and use it for "on-demand" or scheduled scans only.

    Malwarebytes, Immunet Free, ClamWin, and perhaps some other AVs suggest that their product be used as a "second opinion."

    I am almost certain that you will not agree with this, but it is not a bad strategy.  One AV can not find every malware that might be out there.


  4. Anonymous

    Malwarebytes takes control of my computer, locking up screen changes, even locks up in the middle of words an email I'm trying to type. Even to exit or shut off the program takes several minutes before I can again browse, type, or screen change. Malware seems to stop everything and check it before allowing it to appear on screen, either brousing or starting a program on my computer.

    Kaspersky does the same.

    Both do this even if I am not on line, unplugged and disconnected from the service provider.

    Is there a product that does not crank up unseen and lock up what I am doing?

    What good is anti virus if one cannot use the computer when it is working?

  5. Anonymous

    Can i run Kaspersky internet safety at the same time as windows defender?

  6. Anonymous

    Frank: Are you running the premium versions of both security suites? If so, is real-time protection enabled in each? It sounds as though Kaspersky is competing with Malwarebytes for access to your computer's resources.

    Have you added the appropriate files to Kaspersky's lists of Exclusions and Trusted Apps–and vice versa with Mbam?

    if you're confident you've done this correctly, try disabling advanced disinfection technology on Kaspersky.

    If your computer is still acting sketchy, abandon the paid version of Malwarebytes and use it for on-demand scanning only, as guitar Bob suggested.

    If after THAT, you're still experiencing strange activity, download Kaspersky's free TDSS Killer program from their website and run it. Windows Malicious Software Removal Tool is also a nifty little gadget you might want to consider using in the event you are still experiencing problems.

    Kaspersky is hypervigilant and a power-hog, but it shouldn't be dropping anvils on your system… Hope this is helpful.

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