Is there anything in the syslog from just before what you just posted? From the first line it appears that mce told dsme to shutdown and the rest of the log you posted is the process of shutting down.
May 23 21:03:46 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: connection status change May 23 21:03:46 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: install new path: /org/freedesktop/Telepathy/Connection/sofiasip_vox/sip/_xxx_40sip_2evoxcorp_2enet May 23 21:03:46 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: setup_signal_handlers May 23 21:03:46 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: setup_signal_handlers path: /org/freedesktop/Telepathy/Connection/sofiasip_vox/sip/_xxx_40sip_2evoxcorp_2enet/mwi May 23 21:03:46 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: setup_signal_handlers add_signal May 23 21:03:46 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: setup_signal_handlers connect_signal May 23 21:03:46 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: message_counts_table insert. May 23 21:03:46 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: update_msg_counts May 23 21:03:46 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: Trying to update message counts for connection /org/freedesktop/Telepathy/Connection/sofiasip_vox/sip/_xxx_40sip_2evoxcorp_2enet/mwi May 23 21:03:46 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: update_display May 23 21:03:46 Nokia-N900 telepathy-gabble[1560]: GLIB MESSAGE default - lm-ssl-openssl.c: Issued for CN: gmail.com May 23 21:03:47 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: connection status change May 23 21:03:47 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: install new path: /org/freedesktop/Telepathy/Connection/gabble/jabber/xxx_40gmail_2ecom_2fMaemo May 23 21:03:47 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: Refusing to watch a non-vox account. May 23 21:03:49 Nokia-N900 maemo-launcher[1578]: invoking '/usr/bin/modest.launch' May 23 21:03:50 Nokia-N900 maemo-launcher[1578]: opening of /usr/bin/modest.launch took 136078 usec May 23 21:03:50 Nokia-N900 [1578]: activesync: AS-COMMON-UTILS Version: libas-common-utils (0.0.4-12+0m5) unstable; urgency=low May 23 21:03:51 Nokia-N900 [1578]: GLIB MESSAGE default - Hello! modest-nokiamessaging-plugin has been loaded May 23 21:03:51 Nokia-N900 [1578]: GLIB MESSAGE default - CIMSDbusServer::InitDbus acquired connection to dbus May 23 21:03:51 Nokia-N900 [1578]: GLIB MESSAGE default - CIMSDbusServer::InitDbus dbus_bus_request_name succeeded May 23 21:03:51 Nokia-N900 [1578]: GLIB MESSAGE default - CIMSDbusServer::InitDbus dbus_bus_add_match matches=: 2 May 23 21:03:51 Nokia-N900 [1578]: GLIB MESSAGE default - CIMSDbusServer::InitDbus complete May 23 21:03:51 Nokia-N900 [1578]: GLIB MESSAGE default - Loaded! May 23 21:03:51 Nokia-N900 [1578]: GLIB WARNING ** default - Skipped check account due to low diskspace, or no nms account exists in intellisyncd or modest May 23 21:03:52 Nokia-N900 [1578]: activesync: AS-COMMON-UTILS Version: libas-common-utils (0.0.4-12+0m5) unstable; urgency=low May 23 21:03:52 Nokia-N900 [1578]: activesync: AS-CAMEL: Version=camel-as-provider (0.0.4-12+0m5) unstable; urgency=low May 23 21:03:53 Nokia-N900 systemui-tklock[1069]: Method call received from: :1.40, iface: com.nokia.system_ui.request, method: alarm_close May 23 21:03:53 Nokia-N900 [1578]: GLIB WARNING ** mc-client - Unrecognized presence `online' May 23 21:03:54 Nokia-N900 trackerd[1301]: GLIB WARNING ** Tracker - Could not add monitor for path:'/home/user/MyDocs/.camera' May 23 21:03:55 Nokia-N900 trackerd[1301]: GLIB CRITICAL ** Tracker - Could not open directory 'file:///home/user/MyDocs/.camera': No such file or directory May 23 21:03:56 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: connection status change May 23 21:03:56 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: install new path: /org/freedesktop/Telepathy/Connection/spirit/skype/xxx May 23 21:03:56 Nokia-N900 [1168]: GLIB DEBUG tpsip - MWI: Refusing to watch a non-vox account. May 23 21:03:57 Nokia-N900 kernel: [ 70.129974] twl4030_usb twl4030_usb: HW_CONDITIONS 0xd0/208; link 2 May 23 21:03:57 Nokia-N900 ke_recv[1396]: prop_modified:1889: udi /org/freedesktop/Hal/devices/usb_device_1d6b_2_musb_hdrc modified usb_device.vbus May 23 21:03:57 Nokia-N900 [1578]: GLIB CRITICAL ** GLib-GObject - g_type_interface_add_prerequisite: assertion `G_TYPE_IS_INTERFACE (interface_type)' failed May 23 21:03:57 Nokia-N900 [1578]: GLIB CRITICAL ** GLib-GObject - g_param_spec_enum: assertion `G_TYPE_IS_ENUM (enum_type)' failed May 23 21:03:57 Nokia-N900 [1578]: GLIB CRITICAL ** GLib-GObject - g_object_class_install_property: assertion `G_IS_PARAM_SPEC (pspec)' failed May 23 21:03:57 Nokia-N900 [1578]: GLIB CRITICAL ** GLib-GObject - Object class ModestHildonPannableAreaScrollable doesn't implement property 'movement-mode' from interface 'ModestScrollable' May 23 21:04:03 Nokia-N900 [1168]: GLIB CRITICAL ** hildon-1 - hildon_pannable_area_jump_to: assertion `GTK_WIDGET_REALIZED (area)' failed May 23 21:04:03 Nokia-N900 e-addressbook-factory[1186]: GLIB WARNING ** eds/tp - presences_changed_cb at e-book-backend-tp-cl.c:1171: mismatched contact and presence May 23 21:04:04 Nokia-N900 [1578]: GLIB CRITICAL ** GLib-GObject - g_type_interface_add_prerequisite: assertion `G_TYPE_IS_INTERFACE (interface_type)' failed May 23 21:04:04 Nokia-N900 [1578]: GLIB WARNING ** Gtk - SaveToDraftsMenu: missing action ActionsSaveToDrafts May 23 21:04:04 Nokia-N900 e-addressbook-factory[1186]: GLIB WARNING ** eds/tp - presences_changed_cb at e-book-backend-tp-cl.c:1171: mismatched contact and presence May 23 21:04:04 Nokia-N900 last message repeated 4 times May 23 21:04:14 Nokia-N900 systemui-tklock[1069]: Method call received from: :1.11, iface: com.nokia.system_ui.request, method: powerkeymenu_open May 23 21:04:15 Nokia-N900 cellular: csd[823]: ISI_SMS .292755> isiclient_sms_timeout(): TIMEOUT in SMS_STATE_START May 23 21:04:15 Nokia-N900 cellular: csd[823]: ISI_SMS .293121> isiclient_sms_run(): SMS_STATE_START (sms_pp_routing_req, sms_gsm_cb_routing_req, [sms_storage_status_update_req], sim_sms_req_read_parameter) May 23 21:04:15 Nokia-N900 cellular: csd[823]: ISI_SMS .294189> resp_sim_get_parameters(): rc:0 tr_id:0x00, validity:0xe1 May 23 21:04:15 Nokia-N900 cellular: csd[823]: ISI_SMS .294372> resp_sim_get_parameters(): Service centre:'+491710760000' May 23 21:04:15 Nokia-N900 cellular: csd[823]: ISI_SMS .294860> resp_sim_get_parameters(): Alpha:'+' May 23 21:04:15 Nokia-N900 cellular: csd[823]: ISI_SMS .294982> resp_sim_get_parameters(): Service centre:'+491710760000' read from the sim May 23 21:04:15 Nokia-N900 cellular: csd[823]: ISI_SMS .295135> resp_cell_broadcast_subscription(): Incoming cell broadcast receive status:0 OK May 23 21:04:15 Nokia-N900 cellular: csd[823]: ISI_SMS .295288> resp_sms_subscription(): Incoming sms receive status:0 OK May 23 21:04:15 Nokia-N900 cellular: csd[823]: ISI_SMS .295440> resp_sms_resume(): ok internal resume request May 23 21:04:15 Nokia-N900 mce[832]: Error sending with reply to com.nokia.system_ui.request.powerkeymenu_open: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken. May 23 21:04:16 Nokia-N900 mce[832]: Requesting shutdown from powerkey.c: systemui_device_menu_dbus_cb(); result: 5 May 23 21:04:16 Nokia-N900 systemui-tklock[1069]: Method call received from: :1.11, iface: com.nokia.system_ui.request, method: tklock_open