At random intervals, my Linux installation randomly reboots! 
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This could be a hardware issue, such as overheatng, so they system automatically shutdown or reboots if it gets too hot.
does dmesg give you anything, you normally have to type this as root e.g su or use sudo. Perhaps some logs may give a clue.
I am not an expert, so maybe someone who has more #Linux #Logging or #Kernel expertise can help with this.
@zleap
hey, it says to me,
"dmesg: read kernel buffer failed: Operation not permitted"