Saw this happen on two OSX and one Windows box. Everything's fine, and I go EVA (in the latest instance, I don't recall if we were EVA on the OSX instances). The screen goes black. I can pless Esc, and the menu comes up. I can select Space Center. KSP appears as a starry background / skybox. I was able to get out to the game menu from here (Esc again, iirc) The game menu appears as normal. Trying to restart the game returns me to the starry background / skybox Quitting the game and restarting works fine. Doesn't happen every session. No logs (not a crash). In the latest case, on returning to the game, my craft is now on an escape trajectory out of the solar system and the previously EVA pilot is now MIA. Seems the workaround is manually quicksaving before every mission.
