Last week I bought a new model 15" MBP which spontaneous reboots every hour or so. Yesterday I returned it and received a new one (including new power supply etc). This one however does the same. Yesterday evening I started a Time Machine restore which was stopped in the middle because of a spontaneous reboot. I resetted everything (SMC, PRAM, etc.) and tried again. Still reboots after apprx an hour. It doesn't run too hot (67C, 2100RPM). What can be wrong?