I never had this before. Version 4.5.38. Default renderer, only 1400px wide, detail 0.5, AA6, 8gig used from 16 present. Took about an hour to get to this point, but then stopped. No activity anymore. Pressing stop render didn't work, didn't do anything, I could press and release it over and over. So, it didn't look like TG froze or crashed. Shutting down TG had to be forced though. Render wasn't saved in output folder either.