My laptop was shutting down for no apparent reason. I thought it might be overheating, so I ran RealTemp (www.techpowerup.com/realtemp/) and found that overheating was, in fact, the problem. With heavy use, the core temperature easily went above 95 degrees. The CPU shuts down at 100 degrees.
Took the laptop apart and cleaned the radiator on the end of the heatpipe coming from the CPU and GPU. It was pretty badly gunked up with dust.
Works a treat now! Even with heavy use, it’s hard to get the temperature above 60 degrees. The fan is also on less often and is quieter.
Dell Inspiron 1525 laptop, about 3yr old. Intel Celeron 560 processor.