Plethora of startup problems - Windows PC

Plex Players Desktop Players
4
  1. uninstall the player, empty out the folder C:\Users\<yourusername>\AppData\Local\Plex\cache, download the latest installer and run it
  2. see Suddenly black window - plex unsuable - #5 by FordGuy61 for a workaround. (Or avoid starting the player when connected to a screen which is not there all the time.)