I've seen in dmesg some things I wanted to comment to you.

First of all, I've seen a message at boot:

ACPI: System BIOS is requesting _OSI(Linux)
ACPI: Please test with "acpi_osi=!Linux"
Please send dmidecode to linux-acpi@vger.kernel.org

I've tested with that boot option, and I see exactly same message (maybe a 
bug?)

dmidecode is attached.
=========================
I've seen:
ACPI: BIOS bug: multiple APIC/MADT found, using 0
ACPI: If "acpi_apic_instance=2" works better, notify 
linux-acpi@vger.kernel.org
Testing with that option, I see no difference, except the message change, now 
says:
ACPI: BIOS bug: multiple APIC/MADT found, using 2
ACPI: If "acpi_apic_instance=0" works better, notify 
linux-acpi@vger.kernel.org
=========================
I don't know what it is exactly, but I mail you with information requested.

Please let me know if it is useful, and if you need more info, just tell me.

This is a Samsung R70 laptop, intel core2 duo 1800, 2GB ram 'Santa Rosa'.

By the way, info of dmidecode is not 100% correct, I don't know why. This is 
what is not correct:

extract of dmidecode.txt:
====================
Handle 0x000B, DMI type 10, 6 bytes
On Board Device Information
        Type: Sound
        Status: Disabled (***!!! Sound is enabled and fully functional)
        Description: HD-Audio
=======
I wait for your answer, hope this is useful to improve kernel.

David.