Ivy bridge will shut down at 60 degrees. First check your errlog.dat file to see what killed the computer. You can google any unfamiliar codes. Faling that, might want to use the CPU monitor gadget to live monitor your temps. If I remember right you can tell it to autolog to a text file. Stock CPU cooler?
Huh??? Ivy bridge won't shut down at 60c... it shuts down at ~105c .
Anyway if you are idling at 54c-89c (i would expect ~40c on stock cooler), something is wrong with your CPU cooler, You might want to try reapplying it and monitoring the fan speeds