I have been experiencing the same thing.  I never had this happen on an older computer that failed around February.  I replaced it with a new Dell XPS and installed all my previous programs including FSX and its addons.  On this new computer the shutdowns occured after every C-130 landing.  Today I repeatedly experimented with reversing while on a runway using a Saitek Aviator joystick programed to use one of the switches for the F2 (fast throttle reduction) command (the same set up I have used for 4  years).  Only the throttles moved, never the condition levers. I have used this  set up since activiating the new computer,  on other CS products and other addons for reverse thrust with no problem. Today the C-130 seemed to responded correctly to repeatedly reversing on the ground.  I stopped the reverse movements by momentarily advancing the throttles bringing the engines out of reverse and the engines continued running.  I then performed multiple approaches and landings using reverse (activated by a switch on the joystick, not F2, but programmed to perform the F2 function) after touch down and the engines shut down every time.  I'm baffled and cannot find the variable that results in the shut downs.  The only obvious difference between the old computer and the new one is the old one had Windows XP while the new one has Windows 7.  I'm running FSX with Acceleration, just as I did on the old computer.