A questão era que o computador do OP estava sem memória RAM, como evidenciado por essas linhas do syslog:
Mar 28 15:43:50 hugues-HP-ProBook-4530s kernel: [ 5020.228198] Out of memory: Kill process 25673 (node) score 426 or sacrifice child
Mar 28 15:43:50 hugues-HP-ProBook-4530s kernel: [ 5020.228234] Killed process 25673 (node) total-vm:1714884kB, anon-rss:501900kB, file-rss:0kB, shmem-rss:0kB
Mar 28 15:43:50 hugues-HP-ProBook-4530s kernel: [ 5020.264947] oom_reaper: reaped process 25673 (node), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
Mar 28 15:43:57 hugues-HP-ProBook-4530s kernel: [ 5028.658675] sysrq: SysRq : HELP : loglevel(0-9) reboot(b) crash(c) terminate-all-tasks(e) memory-full-oom-kill(f) kill-all-tasks(i) thaw-filesystems(j) sak(k) show-backtrace-all-active-cpus(l) show-memory-usage(m) nice-all-RT-tasks(n) poweroff(o) show-registers(p) show-all-timers(q) unraw(r) sync(s) show-task-states(t) unmount(u) force-fb(V) show-blocked-tasks(w) dump-ftrace-buffer(z)
Mar 28 15:43:58 hugues-HP-ProBook-4530s kernel: [ 5029.400548] sysrq: SysRq : This sysrq operation is disabled.
Mar 28 15:43:58 hugues-HP-ProBook-4530s kernel: [ 5029.752964] sysrq: SysRq : This sysrq operation is disabled.
Mar 28 15:43:59 hugues-HP-ProBook-4530s kernel: [ 5030.203206] sysrq: SysRq : This sysrq operation is disabled.
Mar 28 15:43:59 hugues-HP-ProBook-4530s kernel: [ 5030.733980] sysrq: SysRq : Emergency Sync
No chat, o OP disse que ele só tem 4GB de RAM e troca desabilitada, então ficar sem memória era definitivamente o problema.
A única correção aqui é comprar mais RAM .