Problem with Laptop
 

Just recently my laptop has been just switching off for no reason. Its a Fujitsu Amilo D, couple of years old 2.8g, 512ram.
Think it may be heat related as I have to leave it a few minutes before I switch it back on. Could it just be full of dust/crap etc. Fan still works and changes pitch as I use the machine more.
No blue screen or anything and no error messages when I switch it back on. It just takes a while longer than usual to go through startup.
All help gratefully accepted.
Cheers
Alasdair