Running the latest Parallels 12 under Mac OS Sierra on a Mac Pro (2012) ... multiple Centos 7 VM installation attempts eventually lose the ability for "Full Screen View". The VM works, but displays inside a less than full-screen window with black bars at the top or bottom. While the VM can be shut down from inside using the Centos 7 "Power Off" option, the VM itself cannot be shut-down as far as Parallels is concerned. The red button at the upper left of the VM Mac window is ignored . "Quit Centos 7" from the Parallels menu option is ignored. The only way it can be shut down is to use the Mac OS "force quit" option to force quit Parallels. And it takes a good 3+ seconds to die even then. Under the Parallels "View" menu option, "Enter Coherence", "Enter Full Screen" and "Enter Modality" are all grayed out and cannot be selected when this condition occurs. However, there are a few times which for some unknown reason, upon reboot, will have all the View menu options working. But if the machine is shut down, it is likely the next time it is started it will be in the semi-paralyzed state as far as Parallels handling and screen display. I have tried reinstalling Parallels Tools. This doesn't change anything. I have made new Centos 7 VM's from scratch several times; it always works initially, but then Parallels starts developing erratic problems with the inability to set view options, the black vignetting bars on the display, and shut down of the machine requiring "force quit". Don't have this problem with Centos 5 or Centos 6 installations.