Forced to use "acpi=off" with 64 bits OS, not with 32bits

[Cam]

Hi everyone,

     I'm experiencing difficulties with my laptop, a Samsung R710. I'm currently using Ubuntu Intrepid Ibex, the amd64 OS. As far as I've tested, I've had the same problem using the 64 bits versions of Fedora, and an other linux OS I've forgotten. Let's describe it :

     I've had no trouble using the 32 bit versions of Ubuntu. As my computer was able to use a 64 bits OS (and as it has 4 GB of RAM), I decided to switch to this version. But my laptop crashes a few seconds after booting the kernel. If I erase "quiet splash" from my boot entry, I don't even have the time to read the messages my screen displays before my computer suddenly reboots.

     Using the "rescue" page from doc.ubuntu-fr.org, I found that using "acpi=off" was the only solution to this crash. But the real pity with it is the management of energy. My laptop restarts as soon as i unplug the AC/DC power adaptater.

     So, I'd like to ask you. Will I always have to use this option to use linux 64 ? It appears to be very strange, because everything was allright with the 32 bits versions !

Thanks !

P.S. Here are some details about my hardware and system :

Linux cam-laptop 2.6.27-9-generic #1 SMP Thu Nov 20 22:15:32 UTC 2008 x86_64 GNU/Linux
Ubuntu 2.6.27-9.19-generic

+ the files included after.