Lately, it happens quite often that Windows Defender turns off randomly, without any warning. When I access this application, I find it red and disabled, with the statement "Your PC isn't monitored because the app's service stopped. You should restart it now" ( image https://www.dropbox.com/s/urnjykzno8g6cry/defender%20stopped%2001.jpg?dl=0 ). I click the "Start now" button, and then another statement appears "Real-time protection is turned off. You should turn it on" ( image https://www.dropbox.com/s/zpn7n8igk5qneld/defender%20stopped%2002.jpg?dl=0 ). After I click the "Turn on" button and wait a short while, Windows Defender turns green and says that everything is OK. Later, when I check this application, quite often I find it disabled again and I have to do again the operations described above. This is very annoying because I am not sure anymore that my computer is really protected, and so I am forced to periodically check the status of Windows Defender in order to re-enable it when I find it disabled. This application should stay ON and let me do my work without any disturbances, being confident that my computer is really protected.
My only security applications are Windows Defender and the free version of Malwarebytes Anti-Malware. These two applications never interfered, so there should be no trouble about their simultaneous presence on my computer. Both security applications do not report any infections after full scanning. I checked for other antivirus software on my computer, but I did not find any.
What could be wrong and how can it be solved?