Windows Defender service stops randomly

Suddenly the Windows Defender service keeps turning itself off. I haven't detected a pattern leading to the behavior yet, it just seems to happen randomly. I'll glance down at the icon in the systray and see the red "x". I double-click it, then hit the "Restart" button in the Defender window to get the green checkmark back. Sometimes I open "Services.msc" and will see it's marked as "stopped". I can right-click and restart it that way. In the services list it's set to start automatically and if I open properties all the options are greyed out.

Opening Control Panel\All Control Panel Items\Security and Maintenance it shows Windows Defender is turned on, even when the tray icon has the red "x" and it's marked as stopped in service.msc. If I click on "View installed anti-virus apps" it shows McAffee Anti-Virus and Spyware, but it's set to "Off" and Windows Defender Antivirus set to "On". I didn't install the McAffee stuff, I'm pretty sure it came pre-installed and has been there a while without causing problems. Essentially, the red "x" and Services.msc says the service is stopped, but the Security and Maintenance window says it's on. I can run a scan no problem.

Tried running SFC and rebooting. Didn't help.

What the what is this nonsense?

This is an HP Envy laptop running Win10x64.

Thanks!

Removed all traces of McAfee. Still happening.

The issue seems to have resolved itself. I'm not sure why, but it's been several days and Defender has not stopped, when before it was stopping several times a day.

If it was something I did, I have no idea what.