My laptop a sony vaio VGN-NW11S http://www.trustedreviews.com/Sony-VAIO-VGN-NW11S-S---15-5in-Laptop_Laptop_review.

Everytime i turn it on, in safe mode or not, if i try to open an application i.e. run a process such as google chrome or event viewer, defrag, virus scan, it completely turns off without warning, nor giving a trace of events the next time I switch it on.

Apart from that, I had worries it might be my battery or power supply but I dont think it is that, I took the laptop apart cleaning fans etc. and have ordered some cpu paste as I checked to see the condition of the processor. I will post to see if re-applying the paste works.

One more thing, when the heavy processes kick in, the fan starts to make a lot of noise, maybe trying to cool down the CPU?

Any ideas on what else it could be and what I could do to test what is wrong?