Here is how to reproduce:
64 MODE DENMAX DENFAC -- fractions of an inch mode
Start 'TRI' solver from library. (I did it trough CAT, select LBL'TRI', XEQ, in case that matters).
"Trigon" : [R/S]
a= : 6.1.2 [R/S]
b= : 4.7.8 [R/S]
c= : 6 [R/S]
alpha= : 0 [R/S]
beta= : 0 [R/S]
gamma= : 0 [R/S]
Solution: [R/S]
-- and calculator shuts down.
This happens on real device every time, did not try on emulator, both my calculators do that. The one with newer firmware blinks "Bye...", so it must be a "proper" shutdown.
It may or may not be related to
LINESQ step through bug, which also shuts down the calculator.