When you say active or non active drive can you explain further?
I am not a technician but my way of understanding it is that it is the part set as the bootable partition on the hard drive that contains the operating system. Rootkits can exploit that area especially on earlier versions of Windows.
Have you ever had a problem like that with Malwarebytes on your computer?
I have the free version that only runs when I ask it to so it is not running all the time.