My laptop recently experiences random shotdown problem. While working for a couple of hours, then all of a sudden it shotdown by itself, just powers off complete. After pressing power button it will start working again, from normal login screen, not "Windows is resuming". It's almost three years old. Had the cooling fan replaced in the first year and runs OK up to now. The fan runs OK while the laptop is on. definitely not power outlet problem since this happens in different places. Any thoughts what's the cause? Must be heat related since it will occor after a while. Power supply component failure? time to toss out and get a new one?? Thanks !!