Strange problems with Windows Defender



Hello, all,

I have been trying to correct some issues I have had with my copy of Windows
Defender for several weeks, but nothing seems to help. I am running Defender
on a laptop with Windows Vista, 32-bit, and Service Pack 2. I use Avira and
avast! as third-party anti-virus sources, Comodo for a third-party firewall,
and Spybot S&D as my only other anti-spyware program.

The first symptom I noticed from Defender was that it was taking a very long
time to load after log-in. Not long after, I noticed that, sometimes, the
program would seem to load only partly, with the user interface featuring
only a few buttons on the toolbar without any labels and a large, black space
where the status summary pane of the window would otherwise have been.
Furthermore, the right-click menu for the program's taskbar icon would
apparently feature two items (that would highlight as I took my mouse pointer
over them), but no corresponding text labels. The menu commands themselves
still seemed to work; the first brought up the user interface, while the
second would shut down the program.

Over time, as I investigated further the state of Defender on my machine, I
found more symptoms of whatever was going wrong: I don't recall whether the
Windows Defender application service is normally labelled "WinDefend," but
that is the only reference I can now find on the Services list of the
administrative tools. There is now no description given of this service
other than, "<Failed to Read Description. Error Code: 15100>," and upon
trying to view the properties of this service, I am met with, "Configuration
Manager: A general internal error occurred," followed by, "The resource
loader failed to find MUI file."

I have received no general error message or code while trying to work with
the program itself or its user interface (only the black screen and empty
labels that make it very difficult to use in any event). I suspect that
whatever is faulty with the program, it requires a fresh copy of its data,
but I have encountered trouble regarding that, too. In my research, I have
gathered that, as a program, current versions of Defender in Windows Vista
trace back to the KB931099 update, and that any attempt to replace Defender
must involve the removal of this update package. Unfortunately, my attempts
to do so only result in yet another error message, this one along the lines
that the update could not be removed.

I am at a loss for how to proceed at this point. My choices now seem to be
to give up on Defender and prevent it from trying to load in the future, or
to recover Windows Vista in its entirety, which I am not sure I can do
without resetting my laptop to its factory-default state. I would appreciate
it if anyone has any insight, either about what I can attempt to repair the
issue, given what information I have so far about the problem, or about what
information I still lack to make a more definitive diagnosis.

Yours perplexedly,


Do you understand that you've got two (2) anti-virus applications installed
and loading at boot?

"Do not use more than one anti-virus, 2 or more is a sure way to hit trouble,
just as with firewall's."

Try running the command "sfc /scannow"
in a elevated command prompt.

See whether that takes care of it.

You can look here for details on it.

How Open Command Prompt as Administrator on Elevation in Vista

How to Repair and Verify the Integrity of Vista System Files with System
File Checker>

Close the elevated command prompt when it finishes. Type EXIT, press ENTER,
and that will close the CP window.


Bill Sanderson

I agree with Engel's advice---sfc /scannow seems the right prescription.

I'd sure like to know what is going wrong, though. Windows Defender is part
of the OS in Vista, and can't be separately installed or uninstalled. It
isn't even one of the optional pieces which can be active or not. You can
disable it by opening the app and going to tools, options, and unchecking
the box to "use Windows Defender" or something similar. Or, you can set
service startup to disabled, but that is worth avoiding if possible.


Thank you for your reply.

I understand that I have two anti-virus programs running simultaneously.
Avira has a better virus database than avast!, while avast! has a better
real-time protection system than Avira. I can't imagine that Windows
Defender has become the collateral damage of some conflict between the two; I
have never seen two anti-virus programs cause problems on a Vista or XP
system *unless* one (or both) of those anti-virus programs was part of a
security suite of applications that included a software firewall that ran in
conflict with another firewall. In such cases, the problems didn't stem from
having multiple anti-virus programs, but from having multiple software

Activating SFC has produced no results. The response I receive from the
command is that there is another repair process pending and that I must
reboot the computer and run the SFC command again. I have done that three
times now, with one attempt in Safe Mode, and the response is always the same
as the first.

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