iMac shutting down when exporting or entering color correction tab

Hello, I'm experiencing some issues with Premiere Pro and my 2017 iMac.

A few days ago when I was trying to export some material through Media Encoder using Mercury Playback Engine GPU Acceleration, my iMac simply SHUT DOWN. This happened also not using Media Encoder. So I had to export without the GPU... After a few days, I had other some problem with my Finder and had to format the iMac. After formating, I was able to do export via GPU.

But now I'm having some issues with the Color Correction tab. Whan I click to use the color correction tools, my iMac shut down immediately

Can anyone please save my life? Thanks!