I searched here and found talk of this pest, but did not see any solution to get rid of it. Every week or so we get a "Apple Security Center... blah blah" message that locks up our screen; older Mac laptop. We can get rid of it fairly easily, but it is annoying. MalwareBytes does not detect anything on the iMac. Is there a way to either block this thing or rid it from the laptop if it is hiding there somewhere? Thanks.