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Windows 7: Windows Defender - unable to start

21 Nov 2016   #1

Windows 7 Home Premium
Windows Defender - unable to start

I've tried everything listed in the various help pages, still unsuccessful. No other antivirus programs installed. Ran SFC scan, no errors found. Finally got to the app screen (after services.msc > Automatic > Restart), clicked on Update Definitions, started to update then aborted with error ox80004004. Don't see any way to uninstall and reinstall since Defender does not appear in the Programs list. Any ideas? Thanks!

My System SpecsSystem Spec
21 Nov 2016   #2

OEM Windows 7 Ult (x64) SP1


This doesn't answer your specific question or address your specific issue, but...

...Windows Defender (WD) under Win7 is just a weak anti-malware/anti-spyware application.
It is NOT an anti-virus (AV) application on that platform.
Even with WD running, you would still need a real-time AV, either free or paid.
And there are better choices for real-time anti-malware protection to help prevent infection alongside your AV.
So,by itself, I would not worry about WD's being broken.

Having said that,
you said: "No other antivirus programs installed".
If, in fact, you've been running with only WD and without a bonafide, real-time AV, then it's possible (likely?) that you may be infected and the malware could be preventing you from turning on WD.

You may need to get some help running some scans to see what's lurking on the system.
Aside from WD being disabled, what other signs/symptoms/abnormal behavior are you experiencing to suggest possible infection?

My System SpecsSystem Spec
21 Nov 2016   #3

W7 home premium 32bit/W7HP 64bit/w10 tp insider ring

Hi Weamish,
can you confirm whether its just Defender or MS security Essentials.

My System SpecsSystem Spec


 Windows Defender - unable to start

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