Im having the same problem , ive got this toshiba a300 which is quite old , now its shutting off randomly when u turn it on but when i go safe mode it stays , i ran linux and it shuts off after couple of minutes but when i run in compabitliy mood it didnt do it , i have tested the hdd and ram and all good , so i suspected the graphic card driver or maybe another driver , i updated bios and installed the original windows that came with it ,so far no problem but only two drivers in the driver list still not installed and i also noticed , the network driver had some weird name "isatap.{01f5587B-D8D1-43AC-8FF1-E9E8FF3BACBF} and another one istap.{CAAA7E60-ADAB-40C1-A2F7-650D5049E18} so i disabled them and its working fine so far and will post if anything happens . If anyone have an advice or can have any knowledge about what is going on let me know plz