Comment 37 for bug 285892

Attention: a not simple workaround has been found for some of us (specially Samsung hard disk/bios users), look at this link:

http://wiki.archlinux.org/index.php/Samsung_N140

Please, kernel developers of Ubuntu, insert these workarounds in the next kernel version:

Here I copy the relevant parts:

---
Possible BIOS problem causes a SATA hardreset shortly after boot. This is unresolved up to Samsung N140 BIOS 04CU, and Samsung N130 BIOS 05CM, although a kernel patch is being investigated. See http://bugzilla.kernel.org/show_bug.cgi?id=14314, http://bugzilla.kernel.org/show_bug.cgi?id=13416, http://lkml.indiana.edu/hypermail/linux/kernel/0908.2/02809.html and http://lkml.indiana.edu/hypermail/linux/kernel/0911.3/01604.html .
A summary of the status as currently understood:
About 5 minutes after boot or resume, the BIOS switches on some power saving features which were not enabled at boot. It enables additional (sleepier) processor C-states, and sends power management instructions to the HDD. It does these behind the operating system's back -- not using ACPI, which would be handled correctly by Linux. Instead the sudden change results in a SATA exception at the first disk access following the switch. At that point the SATA driver resets the disk to resolve the problem. The result: the user sees a complete system freeze for about 30 seconds, after which operation of the machine continues normally. This can occur during the periodic fsck at boot if it is running at switch time. Either Samsung needs to be convinced to fix the BIOS, or the Linux kernel needs to be modified to behave more gracefully (Windows doesn't freeze noticeably if at all).
It has been reported that some OpenSUSE kernels [1] do not freeze and testing is progress in the Arch Forums. The patch libata-ata_piix-clear-spurious-IRQ has been reported to resolve the freezing problem. (Hint: to look at the rpm use rpmextract, and then untar config.tar.bz2 and patches.*.tar.bz2).
There is a kernel patch available which changes the backlight brightness using SMI instead of poking PCI config space. It provides a kernel module called "samsung-laptop". Interestingly a special (as yet unreleased?) BIOS for the N130 can be informed that the OS is Linux by a version of this patch which is included in OpenSUSE 11.1. The effect of this hasn't been published.
The N140 and N130 BIOSes have Phoenix FailSafe (you have been warned). It's not clear if the SATA problem has any relation to this.
Version 01CM of the N130 BIOS has been reported to not cause freezes, unlike all later ones which do.
This problem is hazardous for your filesystem so take precautions. For example use ext3 (not ext4) with option data=journal and install backup software.