Windows Defender -- new twist on the uninstall / reinstall question RRS feed

  • Question

  • The short version of this question is how can I reinstall Windows Defender on the Vista OS?

    I'm working on a family member's PC that is about 6 months old, running Windows Vista, up to date on all Windows updates, running AVG Antivirus, firewall in order etc.  This is a good clean setup.  I've read through every forum here and on Google searches about the error "You don't need to install this program...." when trying to install Windows Defender on a Vista machine.

    Yes, I've heard you "can't uninstall it because it's part of Vista".  HOWEVER, my family member clicked one of the AV phishing scams and downloaded "Green Antivirus" and "Personal Antivirus", both of which are known malware.


    The service exists, but I get an error when starting it because none of the files are there.  It's not listed in Add | Remove Programs, of course, and THERE ARE NO FILES IN C:\PROGRAM FILES\WINDOWS\WINDOWS DEFENDER. 

    So let's avoid the answer that "you can't really uninstall it, just start the service and you'll be fine".  The virus did indeed uninstall it or zap the files or something.

    So anway, how on earth do I get it back if I can't run the MSI from Microsoft?  I've tried restore points and all of that to no avail. 

    At the moment, I don't have the original setup CD's that came with the PC, but my next step would be to try to repair the Vista installation......but that option scares me to death.  Why, oh why, can't I simply install this mediocre anti-spyware package without having to get back into the OS? 

    Someone please tell me there's a way!

    I've been pretty pleased with Windows Defender since they bough it from Giant or whatever that company's name was.  I do run Super Antispyware along with it, though, and that's what I've put on this family member's machine for the time being.

    Sorry for the long post but those are the details. 

    Thank you!
    Tuesday, September 29, 2009 8:10 PM

All replies

  • This problem is ongoing, does anyone have any ideas or input?  Thanks!
    Tuesday, October 27, 2009 7:17 PM
  • Due to it been part of Vista just like Media player is id say it requres a re-install of the OS, the Malware could possibly have Corrupt and deleted the files from the Registry.

    do you have a backup of the registry before all this happened?

    Try a OS repair from a CD allso

    let me know how you get on.
    Thursday, October 29, 2009 1:58 PM
  • I was unable to install from the Windows Defender web page because it was telling me that it was already installed and did not need to install Windows Defender.

    I fixed this by running SFC. Go to a command screen as Adminstrator and enter SFC /SCANNOW.

    It replaced the files that I was missing from the C:\Program Files\Windows Defender folder. 

    Give it a try, only took about 10 minutes.

    Wednesday, December 15, 2010 2:36 AM
  • 1. AVG is SUPPOSED to shut down Windows Defender. It is because AVG has its own defender. Running 2 defenders in the same machine will create conflicts.

    In my Home Premium, I don't need to go through WINDOWS, just.....
    Open C: drive > open Program Files > scroll down to find Windows Defender.

    3. System file check ( SFC ) might be able to fix and repair the corrupt files in Windows Defender, but it will remain turned off as long as you have AVG.

    4. Contrary to what you insisted, Windows Defender is in the system. You will never be able to install another one into the computer.

    Sunday, January 16, 2011 3:59 PM