Interrupt storm detected on "irq20: acpi0"; throttling interrupt source ???

[B.Bonev]

dmesg output:

Copyright (c) 1992-2004 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 5.3-RELEASE-p5 #0: Tue Jan 25 06:15:15 EET 2005
    root at ibb.orac.bg:/usr/src/sys/i386/compile/MYKERN
ACPI APIC Table: <ASUS   P2B-DS  >
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Pentium III/Pentium III Xeon/Celeron (451.02-MHz 686-class CPU)
  Origin = "GenuineIntel"  Id = 0x672  Stepping = 2

Features=0x383fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,
MCA,CMOV,PAT,PSE36,MMX,FXSR,SSE>
real memory  = 268423168 (255 MB)
avail memory = 257204224 (245 MB)
FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
 cpu0 (BSP): APIC ID:  1
 cpu1 (AP): APIC ID:  0
ioapic0 <Version 1.1> irqs 0-23 on motherboard
npx0: [FAST]
npx0: <math processor> on motherboard
npx0: INT 16 interface
acpi0: <ASUS P2B-DS> on motherboard
acpi0: Overriding SCI Interrupt from IRQ 9 to IRQ 20
acpi0: Power Button (fixed)
Timecounter "ACPI-safe" frequency 3579545 Hz quality 1000
acpi_timer0: <24-bit timer at 3.579545MHz> port 0xe408-0xe40b on acpi0
cpu0: <ACPI CPU> on acpi0
cpu1: <ACPI CPU> on acpi0
acpi_button0: <Power Button> on acpi0
pcib0: <ACPI Host-PCI bridge> port 0xcf8-0xcff on acpi0
pci0: <ACPI PCI bus> on pcib0
agp0: <Intel 82443BX (440 BX) host to PCI bridge> mem
0xe4000000-0xe7ffffff 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)
isab0: <PCI-ISA bridge> at device 4.0 on pci0
isa0: <ISA bus> on isab0
atapci0: <Intel PIIX4 UDMA33 controller> port
0xd800-0xd80f,0x376,0x170-0x177,0x3f6,0x1f0-0x1f7 at device 4.1 on pci0
ata0: channel #0 on atapci0
ata1: channel #1 on atapci0
uhci0: <Intel 82371AB/EB (PIIX4) USB controller> port 0xd400-0xd41f irq
19 at device 4.2 on pci0
uhci0: [GIANT-LOCKED]
usb0: <Intel 82371AB/EB (PIIX4) USB controller> on uhci0
usb0: USB revision 1.0
uhub0: Intel UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub0: 2 ports with 2 removable, self powered
pci0: <bridge, PCI-unknown> at device 4.3 (no driver attached)
ahc0: <Adaptec aic7890/91 Ultra2 SCSI adapter> port 0xd000-0xd0ff mem
0xdf800000-0xdf800fff irq 19 at device 6.0 on pci0
ahc0: [GIANT-LOCKED]
aic7890/91: Ultra2 Wide Channel A, SCSI Id=7, 32/253 SCBs
fxp0: <Intel 82559 Pro/100 Ethernet> port 0xb800-0xb83f mem
0xde800000-0xde8fffff,0xdf000000-0xdf000fff irq 18 at device 10.0 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: 00:d0:b7:53:a2:be
fdc0: <floppy drive controller> port 0x3f7,0x3f2-0x3f5 irq 6 drq 2 on
acpi0
fdc0: [FAST]
fd0: <1440-KB 3.5" drive> on fdc0 drive 0
ppc0: <ECP parallel printer port> port 0x778-0x77b,0x378-0x37b irq 7 drq
3 on acpi0
ppc0: SMC-like chipset (ECP/EPP/PS2/NIBBLE) in COMPATIBLE mode
ppc0: FIFO with 16/16/9 bytes threshold
ppbus0: <Parallel port bus> on ppc0
sio0: <16550A-compatible COM port> port 0x3f8-0x3ff irq 4 flags 0x10 on
acpi0
sio0: type 16550A
sio1: <16550A-compatible COM port> port 0x2f8-0x2ff irq 3 on acpi0
sio1: type 16550A
atkbdc0: <Keyboard controller (i8042)> port 0x64,0x60 irq 1 on acpi0
atkbd0: <AT Keyboard> irq 1 on atkbdc0
kbd0 at atkbd0
atkbd0: [GIANT-LOCKED]
pmtimer0 on isa0
orm0: <ISA Option ROMs> at iomem 0xd4000-0xd57ff,0xc0000-0xca7ff on isa0
sc0: <System console> at flags 0x100 on isa0
sc0: VGA <16 virtual consoles, flags=0x300>
vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on
isa0
Timecounters tick every 10.000 msec
Interrupt storm detected on "irq20: acpi0"; throttling interrupt source
acd0: CDRW <ASUS CRW-5224A/1.40> at ata1-slave UDMA33
Waiting 5 seconds for SCSI devices to settle
SMP: AP CPU #1 Launched!
da0 at ahc0 bus 0 target 1 lun 0
da0: <IBM DNES-318350W SA30> Fixed Direct Access SCSI-3 device
da0: 80.000MB/s transfers (40.000MHz, offset 31, 16bit), Tagged Queueing
Enabled
da0: 17501MB (35843670 512 byte sectors: 255H 63S/T 2231C)
Mounting root from ufs:/dev/da0s1a

Interrupt storm detected on "irq20: acpi0"; throttling interrupt source
Is this tell me that motherboard have any problem?