I've tried to investigate the problem, and here is my conclusions.

Knoppix boot process hangs immediately after the help page on my Dell Inspiron 5150 (with a 3.06 GHz P4M CPU, Dell BIOS ver. A24,) regardless of the parameters passed to the kernel.

So I installed a stock Debian system (Debian unstable updated daily: the system I'm using right now) in order to reproduce and possibly solve the problem.

I've been able to reproduce exactly the same problem with Debian (using the kernel-source package 2.4.22-2, and building the kernel image locally on my system using
Code:
make-kpkg
.)

The problem arises only when the kernel is compiled with the parameters
Code:
Local APIC support on uniprocessors
 and
Code:
IO-APIC support on uniprocessors
 set (to on.)
These parameters are CONFIG_X86_UP_APIC and CONFIG_X86_UP_IOAPIC respectively.

Note that these parameters are automatically set if one chooses to enable SMP (CONFIG_SMP,) as Knoppix does.

Note also that if you enable the above mentioned siwtches when compiling the kernel, there is no way to boot the system, even if you pass the
Code:
nopaic
(and other similar) parameter(s) to lilo.

The problem is probably due to the fact that the Dell BIOS is buggy (the original BIOS shipped with my Inspiron -- ver. A0 something,) was produced by Compal (the manifacturer of the Inspiron 5150) and not by Dell, and it did not have this problem (though it had a number of other problems.) Unfortunately, when upgrading to Dell BIOS, you have no way to switch back to the original Compal BIOS.
Unfortunately Dell offers no support (and no testing) on Linux, so it is very unlikely that these problems will be corrected by them, as it should be

So the only solution is either wait for a new kernel to circumvent these buggy BIOSes, or wait for Knoppix to permit to boot with different kernels, as you can't boot the kernel in any way once you've compiled it with the above mentioned parameters set

Bye,
Emanuele Zeppieri.
(Italy)