I have exactly the same laptop with the same problem, so I can testify that it is definitely overheating requiring cleaning the power supply. While my laptop was on the warranty, it was cleaned few times by the toshiba authorized agency, now it is out of warranty and I would like to do it myself, however, I have no manual on how to get to it properly and could not yet find easily what I need to unscrew.There are few screws in there requiring a special hexagon-shaped screwdriver, which I don't even have. Tried to open it behind the keyboard on front as it was recommended by one website, however, the power supply and the fan was not there - most likely it is on the back, but I am not able to reach one of the screws, so I might be forced to use the "professional service" which is a waste of both time and money, as usually it takes the repair place a week for something it would have taken me about 1 hour maximum if I had right diagrams and/or instruction on how to open the laptop box! I would be greatful though for an advice on how to get to that damn fan assembly.
Luby, January 2008