It looks like I've found my first kernel bug! :)

Here it is:
http://bugzilla.kernel.org/show_bug.cgi?id=4836

RedHat Enterpise Linux experiences

Lately I work with IBM x346 server. And I want to tell you, that you put yourself in trouble if you decide to install RedHat Enterprise Linux on these machines. The situation is as follows (all software that is discussed here is for x86-64 architecture:

• RH EL 4 series are not officially supported by IBM. In fact, computer just reboots when Anaconda finishes to load X. But if you try text install, things go smooth, and system installs fine, although I did not perform through-out tests. RH EL 4.1 have the same issues. Things like BIOS updates do not change the situation.
• RH EL 3 series ARE officially supported (from Update 5), and I've not noticed any special problems so far, except one: RH EL 3 is OLD. It still uses kernel 2.4.x, which is more exactly 2.4.21 - and they keep patching it until today! Not to mention gnome-2.2 and kde-3.1. Many packages are just not available via RHN, such as Midnight Commander, or Firefox

RH EL 3 feels like dejavue - it strongly reminds me RedHat 9 - good(bad) old days! :)

I just hope that IBM will certify RH EL 4 very soon. But better just throw it all away and install Gentoo