Suddenly, Ubuntu began to reboot itself, what should I do?

Question

HTML

My computer is quite old.
A virtual machine is running, it has photoshop, plus phpstorm, a browser. Doesn't he pull anymore?
Here are the logs.

Jan  4 20:01:38 serii-desktop rtkit-daemon[1468]: Supervising 4 threads of 2 processes of 2 users.
Jan  4 20:01:39 serii-desktop gnome-session[2014]: SSH_AUTH_SOCK=/run/user/1000/keyring/ssh
Jan  4 20:01:39 serii-desktop gnome-session[2014]: SSH_AUTH_SOCK=/run/user/1000/keyring/ssh
Jan  4 20:01:39 serii-desktop rtkit-daemon[1468]: Supervising 4 threads of 2 processes of 2 users.
Jan  4 20:01:39 serii-desktop rtkit-daemon[1468]: Successfully made thread 2180 of process 2137 (n/a) owned by '1000' RT at priority 5.
Jan  4 20:01:39 serii-desktop rtkit-daemon[1468]: Supervising 5 threads of 2 processes of 2 users.
Jan  4 20:01:39 serii-desktop rtkit-daemon[1468]: Supervising 5 threads of 2 processes of 2 users.
Jan  4 20:01:39 serii-desktop rtkit-daemon[1468]: Successfully made thread 2182 of process 2137 (n/a) owned by '1000' RT at priority 5.
Jan  4 20:01:39 serii-desktop rtkit-daemon[1468]: Supervising 6 threads of 2 processes of 2 users.
Jan  4 20:01:39 serii-desktop gnome-session[2014]: SSH_AUTH_SOCK=/run/user/1000/keyring/ssh
Jan  4 20:01:39 serii-desktop rtkit-daemon[1468]: Successfully made thread 2192 of process 2192 (n/a) owned by '1000' high priority at nice level -11.
Jan  4 20:01:39 serii-desktop rtkit-daemon[1468]: Supervising 7 threads of 3 processes of 2 users.
Jan  4 20:01:39 serii-desktop pulseaudio[2192]: [pulseaudio] pid.c: Daemon already running.
Jan  4 20:01:39 serii-desktop dbus[937]: [system] Activating via systemd: service name='org.freedesktop.locale1' unit='dbus-org.freedesktop.locale1.service'
Jan  4 20:01:39 serii-desktop systemd[1]: Starting Locale Service...
Jan  4 20:01:40 serii-desktop dbus[937]: [system] Successfully activated service 'org.freedesktop.locale1'
Jan  4 20:01:40 serii-desktop systemd[1]: Started Locale Service.
Jan  4 20:01:42 serii-desktop dbus[937]: [system] Activating service name='org.freedesktop.fwupd' (using servicehelper)
Jan  4 20:01:42 serii-desktop dbus[937]: [system] Activating via systemd: service name='org.freedesktop.UDisks2' unit='udisks2.service'
Jan  4 20:01:42 serii-desktop systemd[1]: Starting Disk Manager...
Jan  4 20:01:43 serii-desktop gnome-session-binary[2014]: Entering running state
Jan  4 20:01:43 serii-desktop udisksd[2314]: udisks daemon version 2.1.7 starting
Jan  4 20:01:43 serii-desktop dbus[937]: [system] Successfully activated service 'org.freedesktop.UDisks2'
Jan  4 20:01:43 serii-desktop systemd[1]: Started Disk Manager.
Jan  4 20:01:43 serii-desktop udisksd[2314]: Acquired the name org.freedesktop.UDisks2 on the system message bus
Jan  4 20:01:44 serii-desktop gnome-session[2014]: ERROR: Error querying target relations
Jan  4 20:01:44 serii-desktop gnome-session[2014]: ERROR: Error querying target relations
Jan  4 20:01:44 serii-desktop udisksd[2314]: Cleaning up mount point /media/serii/UBUNTU 16_0 (device 8:17 is not mounted)
Jan  4 20:01:45 serii-desktop org.gtk.vfs.AfcVolumeMonitor[1820]: Volume monitor alive
Jan  4 20:01:45 serii-desktop udisksd[2314]: Mounted /dev/sdb1 at /media/serii/UBUNTU 16_0 on behalf of uid 1000
Jan  4 20:01:45 serii-desktop kernel: [   52.716136] FAT-fs (sdb1): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.
Jan  4 20:01:45 serii-desktop org.freedesktop.fwupd[937]: (fwupd:2299): Fu-WARNING **: Failed to coldplug: UEFI firmware updating not supported
Jan  4 20:01:45 serii-desktop dbus[937]: [system] Successfully activated service 'org.freedesktop.fwupd'
Jan  4 20:01:49 serii-desktop pulseaudio[2137]: [pulseaudio] bluez5-util.c: GetManagedObjects() failed: org.freedesktop.DBus.Error.TimedOut: Failed to activate service 'org.bluez': timed out
Jan  4 20:01:49 serii-desktop pulseaudio[1467]: [pulseaudio] bluez5-util.c: GetManagedObjects() failed: org.freedesktop.DBus.Error.TimedOut: Failed to activate service 'org.bluez': timed out
Jan  4 20:01:54 serii-desktop org.gnome.ScreenSaver[1820]: ** Message: Lost the name, shutting down.
Jan  4 20:02:03 serii-desktop dbus[937]: [system] Activating via systemd: service name='org.bluez' unit='dbus-org.bluez.service'
Jan  4 20:02:03 serii-desktop org.gnome.zeitgeist.Engine[1820]: ** (zeitgeist-datahub:2647): WARNING **: zeitgeist-datahub.vala:229: Unable to get name "org.gnome.zeitgeist.datahub" on the bus!
Jan  4 20:02:13 serii-desktop gnome-session[2014]: ** (zeitgeist-datahub:2617): WARNING **: zeitgeist-datahub.vala:212: Error during inserting events: GDBus.Error:org.gnome.zeitgeist.EngineError.InvalidArgument: Incomplete event: interpretation, manifestation and actor are required
Jan  4 20:02:13 serii-desktop systemd[1]: Starting Stop ureadahead data collection...
Jan  4 20:02:13 serii-desktop systemd[1]: Stopped Read required files in advance.
Jan  4 20:02:13 serii-desktop systemd[1]: Started Stop ureadahead data collection.
Jan  4 20:03:20 serii-desktop systemd[1]: Stopping User Manager for UID 108...
Jan  4 20:03:20 serii-desktop systemd[1190]: Reached target Shutdown.
Jan  4 20:03:20 serii-desktop systemd[1190]: Starting Exit the Session...
Jan  4 20:03:20 serii-desktop systemd[1190]: Stopped target Default.
Jan  4 20:03:20 serii-desktop systemd[1190]: Stopped target Basic System.
Jan  4 20:03:20 serii-desktop systemd[1190]: Stopped target Sockets.
Jan  4 20:03:20 serii-desktop systemd[1190]: Stopped target Paths.
Jan  4 20:03:20 serii-desktop systemd[1190]: Stopped target Timers.
Jan  4 20:03:20 serii-desktop systemd[1190]: Received SIGRTMIN+24 from PID 3135 (kill).
Jan  4 20:03:20 serii-desktop systemd[1]: Stopped User Manager for UID 108.
Jan  4 20:03:20 serii-desktop systemd[1]: Removed slice User Slice of lightdm.

Answer 1

I did this: installed avocode, installed photoshop cs6 for editing (if necessary). I haven't turned on virtual yet. So far the flight is normal.