I am with old PC running with Ubuntu 20.04.01 , with a P5GC-MX/1333 motherboard and 2 DDR2 667MHz 2Gb combs, I also use a gforce 8600GT 512Mb video card. But out of nowhere the system freezes and crashes, nothing works and the way is to restart by the physical button. What can be happening? I tried to install Mint Cinnamon-64btis and gave the same problem.