Why did I got crashed/rebooted?

Copyright (c) 1992-2005 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
        The Regents of the University of California. All rights reserved.
FreeBSD 5.4-SECURITY #0: Thu Jun 30 02:25:52 UTC 2005
    root@builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: AMD Athlon(tm) Prosussor (1994.95-MHz 686-class CPU)
  Origin = "AuthenticAMD"  Id = 0x681  Stepping = 1
  Features=0x383f9ff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,MMX,FXSR,SSE>
  AMD Features=0xc0400000<AMIE,DSP,3DNow!>
real memory  = 520028160 (495 MB)
avail memory = 499216384 (476 MB)
npx0: <math processor> on motherboard
npx0: INT 16 interface
acpi0: <KM266P AWRDACPI> on motherboard
acpi0: Power Button (fixed)
Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000
acpi_timer0: <24-bit timer at 3.579545MHz> port 0x4008-0x400b on acpi0
cpu0: <ACPI CPU (3 Cx states)> on acpi0
acpi_button0: <Power Button> on acpi0
acpi_button1: <Sleep Button> on acpi0
pcib0: <ACPI Host-PCI bridge> port 0xcf8-0xcff on acpi0
pci0: <ACPI PCI bus> on pcib0
agp0: <VIA 8235/8237 (Apollo KM400/KM400A) host to PCI bridge> mem 0xe7000000-0xe73fffff at device 0.0 on pci0
pcib1: <PCI-PCI bridge> at device 1.0 on pci0
pci1: <PCI bus> on pcib1
pci1: <display, VGA> at device 0.0 (no driver attached)
fxp0: <Intel 82550 Pro/100 Ethernet> port 0xd000-0xd03f mem 0xe7400000-0xe741ffff,0xe7420000-0xe7420fff irq 10 at device 8.0 on pci0
miibus0: <MII bus> on fxp0
inphy0: <i82555 10/100 media interface> on miibus0
inphy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
fxp0: Ethernet address: xx:xx:xx:xx:xx
isab0: <PCI-ISA bridge> at device 17.0 on pci0
isa0: <ISA bus> on isab0
atapci0: <VIA 8235 UDMA133 controller> port 0xe000-0xe00f,0x376,0x170-0x177,0x3f6,0x1f0-0x1f7 at device 17.1 on pci0
ata0: channel #0 on atapci0
ata1: channel #1 on atapci0
acpi_tz0: <Thermal Zone> on acpi0
orm0: <ISA Option ROM> at iomem 0xc8000-0xc97ff on isa0
pmtimer0 on isa0
atkbdc0: <Keyboard controller (i8042)> at port 0x64,0x60 on isa0
atkbd0: <AT Keyboard> irq 1 on atkbdc0
kbd0 at atkbd0
ppc0: parallel port not found.
sc0: <System console> at flags 0x100 on isa0
sc0: VGA <16 virtual consoles, flags=0x300>
sio0: configured irq 4 not in bitmap of probed irqs 0
sio0: port may not be enabled
sio0 at port 0x3f8-0x3ff irq 4 flags 0x10 on isa0
sio0: type 8250 or not responding
sio1: configured irq 3 not in bitmap of probed irqs 0
sio1: port may not be enabled
vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on isa0
Timecounter "TSC" frequency 1994945792 Hz quality 800
Timecounters tick every 10.000 msec
ad0: 78533MB <HDS728080PLAT20/PF2OA21B> [159560/16/63] at ata0-master UDMA133
Mounting root from ufs:/dev/ad0s1a
WARNING: / was not properly dismounted
WARNING: /home was not properly dismounted
WARNING: /tmp was not properly dismounted
WARNING: /usr was not properly dismounted
WARNING: /var was not properly dismounted
WARNING: /var/tmp was not properly dismounted
IP Filter: v3.4.35 initialized.  Default = pass all, Logging = enabled
pid 564 (perl5.8.7), uid 1002: exited on signal 10 (core dumped)
pid 563 (perl5.8.7), uid 1002: exited on signal 10 (core dumped)
pid 568 (perl5.8.7), uid 1002: exited on signal 10 (core dumped)
pid 569 (perl5.8.7), uid 1002: exited on signal 10 (core dumped)
pid 570 (perl5.8.7), uid 1002: exited on signal 10 (core dumped)
pid 571 (perl5.8.7), uid 1002: exited on signal 10 (core dumped)
pid 572 (perl5.8.7), uid 1002: exited on signal 10 (core dumped)
pid 573 (perl5.8.7), uid 1002: exited on signal 10 (core dumped)
pid 574 (perl5.8.7), uid 1002: exited on signal 10 (core dumped)
pid 575 (perl5.8.7), uid 1002: exited on signal 10 (core dumped)
pid 576 (perl5.8.7), uid 1002: exited on signal 10 (core dumped)
pid 577 (perl5.8.7), uid 1002: exited on signal 10 (core dumped)