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Windows 10 Update KB4020821 Issue

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A Weird thing happened last night after I ran "Security Update for Adobe Flash Player for Windows 10 Version 1703 for x64-based Systems (KB4020821)".

After the update, the Windows Defender Icon made an uninvited appearance in the extended taskbar (or whatever the little window containing the sound icon etc is called). On opening the new, self-announced Windows Defender, by clicking on its icon, I noticed that there was no possibility to scan the computer. Another Anti-Virus program automatically assigned to do that work on my computer could be discovered by clicking on "View antivirus providers" inside the new Windows Defender interface.

My computer was much slower than usual and seemed under stress. So I quickly uninstalled Panda AntiVirus, which I had been using in conjunction with Malwarebytes Premium. This seemed to improve my computer's performance a bit. But the loss of the "second leg" of my security system (Panda) made me feel uncomfortable. I clicked on "View antivirus providers" inside the new Windows Defender interface. It turned out that Malwarebytes was now the only program guarding against viruses and other malware on my computer. 

My next step caused a disaster. I downloaded and installed Avira AV, to see if Avira might be accepted by the new Windows Defender as "co-worker" of Malwarebytes. The computer went beserk.  I could only get back into my files after doing a bootup lasting more than ten minutes.

The question is whether Malwarebytes is enough to take care of ALL Virus & Malware & Hacking threats. If nothing else is needed to guard against any form of threat, I could live with the new Windows update KB4020821.

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Thanks. It was not really a security update but a feature update of Windows 10 (Feature update to Windows 10, version 1703) that caused the problem I wrote about. Since that Windows 10 update, I have not been able to use Panda AntiVirus as a companion to Malewarebytes Premium 3, with Avira faring even worse. The boot-up of Windows 10 is delayed forever and might even end in a crash. What IS possible, is to simply revert to Windows Defender, an Anti-Virus program in itself, as companion to Malwarebytes Pemium 3. What worries me, is that Panda AntiVirus occasionally picked up something missed by Malwaresbytes Premium 3. Not often, but it did happen. Will Windows Defender be as good as Panda in serving the same double-checking purpose?

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  • Root Admin

Unfortunately there is no 100% bulletproof solution. On any given day product x will detect what product y does not, then the next day it can be that y finds what x does not, and back and forth.

I might suggest a couple potential fixes to see if they work for you or not.

I'd recommend you try a Clean Removal of Malwarebytes 3 as well as removal of Panda or other antivirus. Then before you reinstall, run the following.


1. Open a CMD Window as an Administrator on the computer and enter the following commands:


  • cd %windir%\system32\
  • lodctr /R
  • cd %windir%\sysWOW64\
  • lodctr /R


    Note: This command resyncs the counter values.


2. Open up Regedit and navigate to the following registry key:




3. Make sure that the value (if it exists) for the Disable Performance Counters is not 1.  If the entry does exist and the entry is 1, change it to 0 or delete that entry within the key.  ** PLEASE NOTE ** make sure you contact your system administrator before making changes to the registry, and make sure that you back it up before you delete it.


4. Restart Windows


Then reinstall Panda Antivirus and see how it runs without Malwarebytes. Update it, do a system scan, etc. Then if all is good restart the computer again and after next login go ahead and install Malwarebytes 3 and activate it and update it and do a Threat Scan. Then reboot and see if the issue is fixed or has returned and let me know.




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