It's not as simple. Yesterday I was running it for hours, even unloading and loading the battery, on the 'Performance on demand' setting of Jupiter, and it was fine scaling up the CPU clock. Then at one point, while I was using the same applications as before, the problem described above occurred again and stayed like that until I shut the computer down. It may be a mixture of several issues. Until I find out what causes it, my strategy will be to limit heat generation to avoid it occurring.
So I'm guessing you're going to buy some sort of cooler then?