Session blocks and Journal reports "Screensaver started"

LukMas

Without any notice, sometimes during working the current session blocks and the system should be restarted. To be correct, the mouse is still active, because I can move it around, but nothing works. Checking the content of Journal I've found out that just before the restart (needed because the System is unusable) the ScreenSaver service is activated.
lug 24 09:34:40 lap-luca dbus-daemon[222264]: [session uid=1000 pid=222262] Successfully activated service 'org.gnome.ScreenSaver'

At restart there's this message:
lug 24 09:36:16 lap-luca gnome-screensav[2009]: screensaver already running in this session

Any hint about this? Could this be the problem that blocks the System?

LukMas

Second time today.
More info from the journal.
lug 24 14:19:21 lap-luca org.a11y.Bus[42030]: SpiRegistry daemon is running with well-known name - org.a11y.atspi.Registry lug 24 14:19:21 lap-luca org.a11y.Bus[42024]: dbus-daemon[42024]: Successfully activated service 'org.a11y.atspi.Registry' lug 24 14:19:21 lap-luca org.a11y.Bus[42024]: dbus-daemon[42024]: Activating service name='org.a11y.atspi.Registry' requested by ':1.0' (uid=1000 pid=42004 comm="/usr/bin/gnome-screensaver --no-daemon " label="unconfined") lug 24 14:19:21 lap-luca dbus-daemon[42001]: [session uid=1000 pid=41999] Successfully activated service 'org.gnome.ScreenSaver' lug 24 14:19:21 lap-luca gnome-screensav[42004]: Couldn't get presence status: The name org.gnome.SessionManager was not provided by any .service files lug 24 14:19:20 lap-luca dbus-daemon[42001]: [session uid=1000 pid=41999] Successfully activated service 'org.a11y.Bus' lug 24 14:19:20 lap-luca dbus-daemon[42001]: [session uid=1000 pid=41999] Successfully activated service 'org.gtk.vfs.Daemon' lug 24 14:19:20 lap-luca dbus-daemon[42001]: [session uid=1000 pid=41999] Activating service name='org.gtk.vfs.Daemon' requested by ':1.2' (uid=1000 pid=42006 comm="/usr/lib64/at-spi2/core/at-spi-bus-launcher " label="unconfined") lug 24 14:19:20 lap-luca dbus-daemon[42001]: [session uid=1000 pid=41999] Activating service name='org.a11y.Bus' requested by ':1.1' (uid=1000 pid=42004 comm="/usr/bin/gnome-screensaver --no-daemon " label="unconfined") lug 24 14:19:20 lap-luca dbus-daemon[42001]: [session uid=1000 pid=41999] Activating service name='org.gnome.ScreenSaver' requested by ':1.0' (uid=1000 pid=41957 comm="/usr/bin/gnome-screensaver-command -l " label="unconfined")