Hi guys,
I've spent almost one week at the phone with the apple care service in Europe. A very nice guy helped me a lot and is trying to understand this bug.
He told me that they want to solve this problem with the engineers. To do so, every days they called me to do something new to do in order to find the origin of the bug. We have done the reset of SMC, the thing with PRAM, screen captures of the console, going back to Yosemite, and going to EC again etc.
Today, the apple care service called me and made me write a special command in the terminal, then they sent me an apple program to capture data at the moment the computer crash, and it has crashed.... I've sent them a lot of informations to give to the apple engineers so they can make an update or a patch. They also told me that they have read this discussion and they'll try to do their best.
They should call me on monday, the 2nd of november 2.30 Pm, Paris time, if I can get more informations and specially a solution i'll be glad to give it to you here.
My mac pro is a late 2009 4.1, with to GT120 and 2 apple displays 24".
Hope it'll work