problema raro con linux feisty 64

bueno tengo instalado feisty 64bits, y aveces se reinicia la maquina y vuelve a iniciarse como si nada, aca pongo los ultimos logs del system log de linux:

08/06/07 20:53:36 black-pearl gconfd (leandro-6955) Resolved address "xml:readonly:/etc/gconf/gconf.xml.defaults" to a read-only configuration source at position 2

08/06/07 20:53:36 black-pearl gconfd (leandro-6955) Resolved address "xml:readonly:/etc/gconf/gconf.xml.mandatory" to a read-only configuration source at position 0

08/06/07 20:53:36 black-pearl gconfd (leandro-6955) Resolved address "xml:readonly:/var/lib/gconf/debian.defaults" to a read-only configuration source at position 3

08/06/07 20:53:36 black-pearl gconfd (leandro-6955) Resolved address "xml:readonly:/var/lib/gconf/defaults" to a read-only configuration source at position 4

08/06/07 20:53:36 black-pearl gconfd (leandro-6955) Resolved address "xml:readwrite:/home/leandro/.gconf" to a writable configuration source at position 1

08/06/07 20:53:36 black-pearl gconfd (leandro-6955) starting (version 2.18.0.1), pid 6955 user 'leandro'

08/06/07 21:11:06 black-pearl gconfd (leandro-6955) Exiting

08/06/07 21:11:06 black-pearl gconfd (leandro-6955) GConf server is not in use, shutting down.

08/06/07 21:17:01 black-pearl /USR/SBIN/CRON[7157] (root) CMD ( cd / && run-parts --report /etc/cron.hourly)

08/06/07 21:24:24 black-pearl kdm[5375] X server for display :0 terminated unexpectedly

08/06/07 21:24:29 black-pearl kdm_greet[7214] Can't open default user face

08/06/07 21:31:51 black-pearl kdm_greet[7214] Internal error: memory corruption detected

08/06/07 21:32:00 black-pearl hcid[5251] Default passkey agent (:1.24, /org/bluez/passkey_agent_7379) registered

08/06/07 21:32:05 black-pearl NetworkManager <information>^IUpdating allowed wireless network lists.

08/06/07 21:32:05 black-pearl NetworkManager <WARNING>^I nm_dbus_get_networks_cb (): error received: org.freedesktop.NetworkManagerInfo.NoNetworks - org.freedesktop.NetworkManagerInfo.NoNetworks.