My computer has been running strong for almost 3 years, recently however it has been shutting down with no warning and no rhyme or reason. I can't get through the windows start-up without it crashing. I renewed the thermal paste last night with no success aside from being able to get open a cpu temp monitor. The temperature began at 53 degrees C and steadily rose till it hit the 70 mark when i promptly shut it down. Does this sound like a cpu cooler issue or something else?