Random Shutdown: Apple Explains What was Wrong!

Well, Apple is not explaining officially what was causing the well-known "Random Shutdown" of the MB, but it has sent the information to the certified Apple centers.
It was an incompatibility problem between some motherboards and some cooling systems.
To solve the issue, the certified Apple Center will have to change the simultaneously the motherboard and the cooling system.
The repair parts sent by Apple to maintenance centers have already been validated, so you can send your MB for repair if it is shunting down randomly.
However, it might have to stay for some days due to the relatively large number of affected notebooks.
For those willing more details: The previous cooling system was expanding more than expected when draining the heat from the CPU, and as a consequence was creating a short-circuit of one of the temperature sensor leading to the emergency shutdown of the notebook.
The cooling system (heat pipes and heat sink) has been modified, including a new connector to the motherboard, that's why one should have both the motherboard and the cooling system exchanged.