A friend of mine had a problem with similar symptoms on his VAIO laptop...
The cooling fan was running continuously, and then after a few weeks of this, the computer started automatically shutting down without warning.
Sony's technical support team wanted him to back up the data and send the computer in, where they would fix it and return it to him "as purchased". Unfortunately, it wouldn't stay powered up long enough to actually backup the data and months of work he had stored on it would be lost if he sent it in. Given that the computer was out of warranty anyway, he decided it couldn't make the situation any worse to take it apart to see if he could find anything obviously wrong.
It turns out that using the computer in dusty rooms (i.e. his house was being rennovated and was essentially a building site) had caused a buildup of dust between the cooling fins around the processor. Without air to circulate around the processor, it was:
1. Overheating
2. Running the fan continuously
3. Automatically initiating an emergency shutdown to protect the processor from heat-inflicted damage when critical temperatures were reached.
He cleaned the dust out from between the cooling fins and has enjoyed many happy weeks of computing ever since.
Having said all that, taking the computer apart is a bit of a drastic action, and you'll probably want to explore other possibilities before considering this. Also, consider the environment in which you use your laptop and decide whether a similar scenario is likely.
Good luck!
ARCrawford.
I noticed tha last few months that the cooling fan on my VAIO notebook is running continuously. When I switch it on, the fan does not run, after few seconds the booting is complete it starts to run and it never stops. It is really annoying, especially when I do presentations.
