Hello,
You were right. I was not using RHEL 4 Update 4 installation CD. Using the proper RedHat CD leads to the same problem (I cannot boot on the installation CD). I will try to ask RedHat for a solution. Thank you for your help
Or just boot from an 4.3 cd and use yum to upgrade. You will have the same thing as installing from a 4.4 cd.
I solved my problem by using the kernel parameter : "acpi=noirq" Thank you for your help