Sometimes when Blender is doing rigid body simulations, it says 'Not Responding' and then after a while it responds again. But when I make the computer 'hibernate', while Blender is in 'Not Responding' state and I resume the computer, then Blender freezes up and I have to close Blender and start everything all over again. What should I do next time, instead of closing Blender and start all over again?
I think you know the answer to this one already. 3D can be one of the of the most computationally intensive activities to throw at a computer. It becomes unresponsive because is busy crunching the numbers to work out your simulation..... Judging by your post, you are indeed pushing your computer to it's limits. Let it do its' job... don't hibernate it... get a book, meditate, go for a walk, interact with other humans. 3D requires a bit of patience sometimes... Once blender has finished is job and your computer is back, bake the simulation and save your file so you don't have to start over
Like the above, but if it's regularly failing to respond during rendering, save a copy to a flash drive (and an external backup drive as well if you have a compatible one,) and then let it render. Just put a sticky note over it and turn the monitor off. Then go out and do something else for a while.