Windows Defender wants to run at startup

Since a very recent reinstall of Windows 10, Windows Defender now keeps wanting to be part of Start-up..In the past it seems to me that it was only activated if your anti-virus protection was off or if none was installed. Now it seems as if the intention of Windows Defender has changed to be actively running when windows starts.

Can I allow it to run along with my antivirus & anti-malware programs?

spunk said:

When you install a 3rd party AV product, Windows Defender automatically disables.
What is your 3rd party AV Software?

-- I know that Windows Defender always used to disable when you have a 3rd. party AV product. But after my recent reinstall of Windows 10, it has put itself into the list of startup programs. I removed it several times and it keeps coming back.

-- I have Kaspersky Total Security 2017 and also running real-time, Reason Core Security (Free).

Upon further investigation, I notice that what's in the startup is the Windows Defender Notification Icon (MSASCuil.exe).

What I'm still not clear on is what's stated within the highlighted bit on the top image below.

The bottom image shows the Windows Defender Notification Icon (MSASCuil.exe) within the Startup.

It is safe to let Defender run as an on-demand file scanner (or periodically scheduled) even with another AV providing real-time protection. Scanning files won't load Defender's memory-resident AV protection, so there should be no conflict.

MSASCuiL is the user interface and puts the icon in the notification area. This has been a startup item since 1607 was released. On its own, MSASCuiL does not load the memory-resident AV either.

Are you sure you actually had 1607 before your recent repair-install? If you had in fact upgraded from 1511 to 1607 then this would be the first time you would have seen this behaviour.

Defender's memory-resident AV services (if running) are shown in Task Manager on the Services tab as WinDefend and on the Details tab as MsMpEng.exe. With your other AV running this should be shown as 'Disabled' in Services. If not, try reinstalling your other AV.

You can make the icon disappear from the notification area by killing MSASCuiL in Task Manager. You cannot remove it from start up (well, you can, but Defender puts it back again at reboot). If you want to make the icon go away...

...you just have kill the task at start-up. You can do this for your user account by putting a .bat file in the folder:
C:\Users\<your_username>\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup
containing the command:
taskkill /im MSASCuiL.exe

For all users you could put it in:
C:\ProgramData\Microsoft\Windows\Start Menu\Programs\StartUp

Cannot remove Windows Defender Tray Icon

The icon will reappear (and stay there until you kill it) if you ever open Defender (because doing so runs MSASCuiL).

I didn't read all of the threads but you can just disable the Defender notifications in the startup tab. That will try to start even if you have a 3rd party AV running in the active mode. Also, I am sure you are aware that you can have some of the AVs running in a passive mode along side of Defender. Avast is one that offers that option but I chose not to use it and now Avast is the exclusive protector of my PC.

Bree said:

Defender's memory-resident AV services (if running) are shown in Task Manager on the Services tab as WinDefend and on the Details tab as MsMpEng.exe. With your other AV running this should be shown as 'Disabled' in Services. If not, try reinstalling your other AV.

Thanks for the info Bree. In the Services tab within Task Manager, WinDefend is shown as stopped (see top image). In the Details tab there is no indication of MsMpEng.exe (see bottom image).

Razz said:

In the Services tab within Task Manager, WinDefend is shown as stopped (see top image). In the Details tab there is no indication of MsMpEng.exe (see bottom image).

Then Defender is set up as it should be when another AV is installed. The optional 'limited periodic scan' is a safe 'second opinion' - up to you whether you leave it turned on.

WOT said:

I didn't read all of the threads but you can just disable the Defender notifications in the startup tab.

That will only work while Defender's real-time protection is turned off (as it is when you have another AV). The first thing MsMpEng.exe does when run is to check all it's registry keys and reset them if they've been modified - including that startup one.