When we make the "damping" and "force" values excessive in the physics engine, the object affected disappears in the preview screen, that is, it is not visible. I have to reopen the project. It happened in the previous version as well. The version I am currently using is 4.2.40. I think there is a problem here. Just so you know.
Yes. The solution is don't do that. 
If it happens, click Reset on the physics constraint.
There are many ways to break the physics math with unreasonable values. For example, you can create an oscillation that grows and grows until it reaches billions or gajillions and exceeds the ability for computers to compute. When that happens the math gets "not a number" or "infinity" values that are invalid and the bones and their attachments disappear.
We can't prevent this from happening. Limiting the magnitude of values isn't a solution, because the same values can be valid depending on other settings. You need the flexibility of being able to enter any values, so you'll just have to be careful not to make physics explode.
