I'm unsure if this is the same thing but my chicken was dying so the grim reaper appeared, but he just stood there or floated about causing my game to stick because of the 'sim is dying' message.
Basically, I zoomed out and looked around the areas outside my lot and saw a bunch of foxes surrounding to elder foxes that were laying down and looked dead. I opened the cheat dialogue box with ctrl + shift + c and typed 'testingcheats true' to turn cheats on, and then I shift/clicked on the 'dead' foxes and clicked on reset. It reset the foxes so they came back to life, and then the camera went to the grim reaper who finally took the chicken and my game returned to normal and I was able to save again etc.
