Thanks:

I will try to check the thermal sensor, and I will change the paste.

Also I want to add that today I notice that the problem show itself sometimes when I move laptop. I was working for two hours without any problem (around 55 C which is normal), Then I closed the lid, took it to my desk and when I opened again, the temp monitor was showing 1C. So it seems to be a loose connetion or something similar.

Thanks again for your answers.