Hi Ikar, Welcome to the the PC Help Forum, I'm glad you've hopped aboard!
It really sounds to me like you have a heat problem. I recommend either downloading Motherboard Monitor 5
at one of the mirror links here..
You could also try removing the side panels of your tower and running a standard household fan (13" oscillating type) through the whole machine. If that stops your machine from hanging then you simply need to add some additional cooling. Otherwise you may be looking at a serious malware issue. But I've found that generally if the mouse cursor stops moving it's heat.
Let us know if those work or not and one of our tech or security experts can take it from there.
Once again, welcome aboard.