For all "official" releases of Knoppix so far "noacpi" does not change anything because ACPI support is not compiled into the kernel. Howerver, what you might want to try is "noapic" (IMO "ACPI" is a very very poor choice of name, easy to confuse with "APIC" even though they are completely different things) If that doesn't help i'd suggest you try all the other cheatcodes available too. (press F2 at the boot prompt to get a list of them)