I had used other anti-virus program on the system.  Now I want to revert back to Windows Defender, but I can't start it.  I try to start the Windows Defender Network Inspection Service and Windows Defender Service.  I get Error 577: Windows cannot verify the digital signature for this file...  I can't change the Startup type to automatic either.  It is dimmed out and disabled to Manual though I have logged in as an administrator.

Hello,

Please refer to following fix and see if it helps you:

http://www.kapilarya.com/windows-could-not-start-the-windows-defender-network-inspection-service

Hope this helps, Good luck :)

I brought up the Action Centre.  I clicked on "Turn on now".  It did nothing.

I checked the relevant registry keys and they were already at the right values, both of which are 1s.

While doing a trial and error last night trying to eliminate any service that would hang the service of Windows Defender, I eventually restored all the services and for some reason the Windows Defender is still working until now.

Only thing that happened in between was that, some Windows updates took place during one of the computer restarts while I was putting services in and out.  So I don't know if the updates rectified the problems by addressing the Windows software fault or reorganising the Windows software while installing the updates and hence removed any corruption in the meantime.

Anytime, I wouldn't say definitely the problem has gone for good for I have not changed anything.  I shall wait and see, and keep you posted.

The updates were as follows.
Windows Malicious Software Removal Tool (KB890830)
Windows 8.1 (KB3027209)
Windows 8.1 (KB3013410)
Windows 8.1 (KB2967917)

-------

While the Windows Defender seems to have started and been working, when I do a scan, it would terminate itself part-way.  When I try to re-start, it comes up with a message as follows.  Sometimes a message to the same effect appears when I try to start right after a computer re-start.

• Edited by healee Wednesday, June 17, 2015 1:01 AM further info

While doing a trial and error last night trying to eliminate any service that would hang the service of Windows Defender, I eventually restored all the services and for some reason the Windows Defender is still working until now.

Only thing that happened in between was that, some Windows updates took place during one of the computer restarts while I was putting services in and out.  So I don't know if the updates rectified the problems by addressing the Windows software fault or reorganising the Windows software while installing the updates and hence removed any corruption in the meantime.

Anytime, I wouldn't say definitely the problem has gone for good for I have not changed anything.  I shall wait and see, and keep you posted.

The updates were as follows.
Windows Malicious Software Removal Tool (KB890830)
Windows 8.1 (KB3027209)
Windows 8.1 (KB3013410)
Windows 8.1 (KB2967917)

-------

While the Windows Defender seems to have started and been working, when I do a scan, it would terminate itself part-way.  When I try to re-start, it comes up with a message as follows.  Sometimes a message to the same effect appears when I try to start right after a computer re-start.

• Edited by healee Wednesday, June 17, 2015 1:01 AM further info

Hi healee,

Have you installed any other antivirus software in the machine?

To isolate a third party conflict issue, we can perform a clean boot to have a troubleshoot.
How to perform a clean boot in Windows
https://support.microsoft.com/en-us/kb/929135

If the issue persists, please run "sfc/scannow" then open an administrator command line and run the following command line to register the related dll files to have a check.
regsvr32 wuaueng.dll
 regsvr32 wucltui.dll
 regsvr32 softpub.dll
 regsvr32 wintrust.dll
 regsvr32 initpki.dll
 regsvr32 wups.dll
 regsvr32 wuweb.dll
 regsvr32 atl.dll
 regsvr32 mssip32.dll

Best r

While doing a trial and error last night trying to eliminate any service that would hang the service of Windows Defender, I eventually restored all the services and for some reason the Windows Defender is still working until now.

Only thing that happened in between was that, some Windows updates took place during one of the computer restarts while I was putting services in and out.  So I don't know if the updates rectified the problems by addressing the Windows software fault or reorganising the Windows software while installing the updates and hence removed any corruption in the meantime.

Anytime, I wouldn't say definitely the problem has gone for good for I have not changed anything.  I shall wait and see, and keep you posted.

The updates were as follows.
Windows Malicious Software Removal Tool (KB890830)
Windows 8.1 (KB3027209)
Windows 8.1 (KB3013410)
Windows 8.1 (KB2967917)

-------

While the Windows Defender seems to have started and been working, when I do a scan, it would terminate itself part-way.  When I try to re-start, it comes up with a message as follows.  Sometimes a message to the same effect appears when I try to start right after a computer re-start.

• Edited by healee 6 hours 12 minutes ago further info

Hi healee,

Do you mean the Windows Defender will work for a while until the four updates installed, right?

We can perform a system restore to recover the machine to a point before theses updates were installed. Then install them one by one manually to have a troubleshoot to find out the culprit.

Best r

I am not too sure now.

I thought the problem had gone.  It seemed working at the time.  However when I did a scan, the process stopped with error message shown above.

I took a wild guess and removed the Advanced System Care Free from www.iobit.com and re-tested it.  Now I have not been able to fault it.  I would leave it for a while so that I can be sure.

At one stage when I put the services in and out to eliminate the culprit, the service that came with the Advanced System Care seemed to be the problem.  However at the end, I found the Windows Defender still ran after I restored all the services, including that of the Advanced System Care.  Then the scan problem happens.  So I decided to remove the Advanced System Care.

Today I have put the Advanced System back and am re-testing it.  I suspect that as long the Advanced System Care serivce is not running, Windows Defender will be fine, perhaps.  I shall keep you posted.

Hi healee,

Is Advanced System Care a third party antivirus software?

Only one antivirus software can be installed on the Windows system and the Windows Defender will be forbidden if there is another antivirus software installed.

Best regards

I am not too sure now.

I thought the problem had gone.  It seemed working at the time.  However when I did a scan, the process stopped with error message shown above.

I took a wild guess and removed the Advanced System Care Free from www.iobit.com and re-tested it.  Now I have not been able to fault it.  I would leave it for a while so that I can be sure.

At one stage when I put the services in and out to eliminate the culprit, the service that came with the Advanced System Care seemed to be the problem.  However at the end, I found the Windows Defender still ran after I restored all the services, including that of the Advanced System Care.  Then the scan problem happens.  So I decided to remove the Advanced System Care.

Today I have put the Advanced System back and am re-testing it.  I suspect that as long the Advanced System Care service is not running, Windows Defender will be fine, perhaps.  I shall keep you posted.

------

I have re-installed the Advanced System Care, and then re-run a scan.  There has been no problem with the Windows Defender so far.  I shall leave it for the time being.

• Edited by healee 23 hours 49 minutes ago further test & further info
• Proposed as answer by MeipoXuMicrosoft contingent staff, Moderator 22 hours 36 minutes ago