After updating to the latest release of Lightroom CC (2015.5) my computer has started shutting down while working in the Develop Module. No error message, or locking up, just my PC rebooting. I have tried turning off Graphics processor acceleration, with no change.
If your system shuts down, reboots, bluescreens, or completely hangs -- you have a problem with the OS, a bug in a low level driver, or defective hardware. Applications cannot cause those behaviors.
The most likely cause would be your video card driver, especially if you have an NVidia driver from a few months back. The next most likely causes would be bad RAM, bad motherboard, bad power supply, bad disk controller, etc.