I too had thought Malwarebytes was one of the more reputable companies - but on two of my hubby's machines that had Malwarebytes installed (a Win 7 and a Win 10) the PCPitstop AV was removed (not just disabled) with no option to white list it and the Windows AV was disabled, leaving those machines without any protection at all. On our other machines (ones without Malwarebytes) if something happens keep one virus scanner from running, the Windows AV will turn on automatically or can be turned on easily. With his two machines, the Windows AV had to be completely reinstalled.
