I had this very same issue when I was a kid with my desktop computer. It turned out my power supply degraded and became insufficient to keep the whole thing powered up when it started reaching full loads. This sounds like a hardware failure more than software honestly. How old is the laptop? Also, try unplugging the laptop for a bit and see how fast the battery runs down. If it is in 2 hours or less, then you probably have a bad power source. =P Also, the SMU might need to be reset if you are running a x86 chip. It is either hardware or the SMU from the sounds of it.