HP pavillion heating up so much as autoclosing!

[Kjetil brinchmann Halvorsen]

Hello!
The last days my laptop HP pavillon with latest updates of Lubuntu
13.10 is heating so much as to shut down automatically, repeataedly.

For the momen the only open programs are chromium (2 tabs only) and
PCmanFM (2 tabs only), but I am hearing the cpu working
as if there was a huge workload!

What is happening?

Kjetil