AP#1 Failed! panic y/n?

[8.0/i386 from today]

Hello,

From time to time, I see this at boot-time on my laptop (a Macbook
pro model 3,1). I'm not sure but it seems related if an USB device is
plugged in one plug (strange because the internal keyboard and the
touchpad are USB devices)

(copied by hand)
Table FACP at 0x7fefc000
Table HPET at 0x7fefb000
Table APIC at 0x7fefa000
MADT found table at 0x7fefa000
APIC: Using the MADT enumerator
MADT: Found CPU APIC ID 0 ACPI ID 0: enabled
SMP: Added CPU 0 (AP)
MADT: Found CPU APIC ID 1 ACPI ID 1: enabled
SMP: Added CPU 1 (AP)
ACPI: APIC Table <APPLE Apple00>
AP #1 (PHY #1) failed!
panic y/n?
(cannot reply because I've got only an USB keyboard)

Also, sometimes the box waits a long time (~20 seconds) at the step
ACPI: APIC Table <APPLE Apple00>, but finally boots fine.

Thanks, regards.