Are you on windows? That sounds really strange indeed -- for some reason, it sounds like something is preventing it from shutting down. And then it's got some assets locked, and/or steam won't let you launch something else after that. If you look in the Processes tab of the Ctrl+Shift+Escape task manager, you should be able to see and kill LastFederation.exe. If steam still thinks it is open, you can restart steam and it will forget. If steam won't restart, you can kill steam.exe via the same method above.
None of those are ideal solutions, obviously, but they prevent a reboot at least. This is honestly a new one on me. You might look inside your LastFederation_Data folder and see what is in your output.log after things have either started-but-failed-to-stop or failed-to-start. Also there are logs inside the RuntimeData folder, too. If you post those we can see what we can do (though on the weekends we're a lot slower than usual, sorry about that in advance).
Thanks for your support, and welcome to the forums!
