I am using Parallels desktop 12 for Mac. My Mac is version 10.14.5 I have shut down the entire computer and restarted, no resolution. I have uninstalled and reinstalled Parallels, no resolution. I had found a video online on how to do ctl-alt-del. But the screen is black and nothing is visible. I know that there is a program in operation on Windows, as I hear notification sounds. My Mac portion of the system works fine. I have lost track of how many headaches I have had with this mess.