This. I had symptoms extremely similar to OPs and saw this in the kernel logs immediately before the system would reset:

[    0.705185] mce: [Hardware Error]: Machine check events logged
[    0.705187] mce: [Hardware Error]: CPU 17: Machine Check: 0 Bank 5: baa0000000090150
[    0.705190] fbcon: Taking over console
[    0.705191] mce: [Hardware Error]: TSC 0 MISC d012000200000000 SYND 4d000020 IPID 500b000000000
[    0.705195] mce: [Hardware Error]: PROCESSOR 2:a20f12 TIME 1678252812 SOCKET 0 APIC 3 microcode a20120a

It turned out to be a hardware issue with my CPU (AMD Ryzen 9 5950X). I got it replaced under warranty (twice actually, the first replacement had other issues) and everything is fine now. Definitely check what the kernel logs say.

You can look at the previous kernel log from before a reboot with journalctl -k -b -1 (as root)

You can do it just in the sketcher and get 90% of the way there with just sketcher constraints. You can also create a body with a subshape binder for each sketch line and use assembly and create an animation. You don’t even need 3d solids. I created a gif, we’ll see if it attaches properly to this reply…