I have an Advent T5250 Portable running Vista Home Edition SP2. Every so often, it might be after 10 minutes or 48 hours, it decides to power off. I get no warning, the screen goes blank and the machine just powers off.

I've Googled around and found out that 'most' problems like this are associated with temperature, but when I feel the case, it's not hot to the touch and the Fan is running. I am about to take the covers off and see whether the fan(s) need cleaning but before I do that I was wondering what other possible causes might be.

As far as I know I've not got any 'nasties', at least AVG doesn't report anything.

I've checked the Power Options and set everything to stay on all the time when running from mains (I don't often use it without it being plugged in as the Battery life is about 10 minutes, fully charged.) Could it be the because the Battery shot to bits, perhaps?