Hi, We have a server which locks up about once a week (for the past 3 weeks now), without any warning, and the only way to recover it, is to reset the server. This causes unwanted downtime, and often software loss as well. How do I debug the server, which runs CentOS 5.2 to see why it locks up? The CPU is an Intel Q9300 Core 2 Quad, with 8 GB RAM, on an Intel Motherboard The last few entries before the server froze, is: Nov 15 07:15:20 saturn snmpd[2527]: Connection from UDP: [127.0.0.1]:59008 Nov 15 07:15:20 saturn snmpd[2527]: Received SNMP packet(s) from UDP: [127.0.0.1]:59008 Nov 15 07:15:20 saturn snmpd[2527]: Connection from UDP: [127.0.0.1]:47729 Nov 15 07:15:20 saturn snmpd[2527]: Received SNMP packet(s) from UDP: [127.0.0.1]:47729 Nov 15 07:15:20 saturn snmpd[2527]: Connection from UDP: [127.0.0.1]:47890 Nov 15 07:15:20 saturn snmpd[2527]: Received SNMP packet(s) from UDP: [127.0.0.1]:47890 Nov 15 07:15:20 saturn snmpd[2527]: Connection from UDP: [127.0.0.1]:50023 Nov 15 07:15:20 saturn snmpd[2527]: Received SNMP packet(s) from UDP: [127.0.0.1]:50023 Nov 15 07:15:20 saturn snmpd[2527]: Connection from UDP: [127.0.0.1]:58459 Nov 15 07:15:20 saturn snmpd[2527]: Received SNMP packet(s) from UDP: [127.0.0.1]:58459 Nov 15 10:10:10 saturn syslogd 1.4.1: restart. Nov 15 10:10:11 saturn kernel: klogd 1.4.1, log source = /proc/kmsg started. Nov 15 10:10:11 saturn kernel: Bootdata ok (command line is ro root=/dev/System/root) Nov 15 10:10:11 saturn kernel: Linux version 2.6.18-92.1.17.el5xen (mockbuild at builder10.centos.org) (gcc version 4.1.2 20071124 (Red Hat 4.1 .2-42)) #1 SMP Tue Nov 4 14:13:09 EST 2008 Nov 15 10:10:11 saturn kernel: BIOS-provided physical RAM map: Nov 15 10:10:11 saturn kernel: Xen: 0000000000000000 - 00000001ef958000 (usable) Nov 15 10:10:11 saturn kernel: DMI 2.4 present. Nov 15 10:10:11 saturn kernel: ACPI: LAPIC (acpi_id[0x01] lapic_id[0x00] enabled) Nov 15 10:10:11 saturn kernel: ACPI: LAPIC (acpi_id[0x03] lapic_id[0x02] enabled) Nov 15 10:10:11 saturn kernel: ACPI: LAPIC (acpi_id[0x02] lapic_id[0x01] enabled) Nov 15 10:10:11 saturn kernel: ACPI: LAPIC (acpi_id[0x04] lapic_id[0x03] enabled) Nov 15 10:10:11 saturn kernel: ACPI: LAPIC_NMI (acpi_id[0x01] dfl dfl lint[0x1]) Nov 15 10:10:11 saturn kernel: ACPI: LAPIC_NMI (acpi_id[0x02] dfl dfl lint[0x1]) Nov 15 10:10:11 saturn kernel: ACPI: IOAPIC (id[0x02] address[0xfec00000] gsi_base[0]) Nov 15 10:10:11 saturn kernel: IOAPIC[0]: apic_id 2, version 32, address 0xfec00000, GSI 0-23 Nov 15 10:10:11 saturn kernel: ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl) Nov 15 10:10:11 saturn kernel: ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level) -- Kind Regards Rudi Ahlers