Cannot Uninstall Windows Defender



On windows XP, I encountered a system problem which forced me to perform a
system restore. I now have the issue where Windows Defender want to
continually update itself. Using the control panel to perform a change
results in the error message "The installed product does not match
installation source(s). Until a matching source is provided or the installed
product and source are synchronized, this action cannot be performed." and it
give me the chance to another source. When I use the WindowsDefender.msi
file that I downloaded, the error message "the MSI file is not a valid
installation package for the Windows Defender. Try to find the installation
package 'WindowsDefender.msi' in a folder from which you can install Windows
Defender. When I attempt to remove Windows Defender through 'Add or Remove
Programs', I get the same error messages as with the change process.

When I use the 'Run' command and enter
"Msiexec /x {A5CC2A09-E9D3-49EC-923D-03874BBD4C2C}" I get the error message
"This package could not be opened. Verify that the patch package exists and
that you can access it or contact the application vendor to verify that this
is a valid Windows Installer patch package."

The Windows Defender system information of the product I am attempting to
remove is Windows Defender Version 1.1.1051.0, Engine Version
1.1.1185.0, Signature Version: .

Any help would be appreciated.


It sure is nice when you find someone has the same problem and already
has a solution. Thanks to All. I am off to see if it works for me.


I have posted this on other sites, but in XPpro/SP2:

I also could not update Defender and to unibstall it I had to go "MY
Computer/Defender" and uninstall its bits one by one, then went through
Search and Regedit to wipe out any reference to Defender. Rebooted, and
re-installed and opened it. The signature detail reverts back to
Then ran Msiexec /x {A5CC2A09-E9D3-49EC-923D-03874BBD4C2C} sucessfully. I
was able to update via the tab to the right of the questionmark to the latest
version !5th March)

Hope this helps. Microsoft are aware of the problem but reminds me that it
is a beta product


Thanks for posting the details. Sorry it was such a pain, and I'm glad you
managed to get it where it will update.

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