I have an older server I am trying to update to CentOS 4.3 but I can't get to the installer screen because the machine kernel panics when booted from the install CD. The error message I get is: Kernel panic - not syncing: include/linux/smp_lock.h:25 spin_unlock(kernel/sched.c:c035) not locked The boot messages before this point are mainly to do with acpi including: acpi_ps_parse_anl acpi_?s_one_complete ... acpi_early_init start_kernel Kernel panic .... At a guess, I tried starting the installer with the options: linux text acpi=off noprobe I am not really clear on what part of the boot process is failing so I tried a number of random boot options including apm=off, noapic, apic, nomce. Nothing I tried change the error. (I also tried installing RHEL 4 but I got the same failure with less informative error reporting: Kernel panic - not syncing: Attempted to kill the idle task!) I also tried changing my BIOS options - changing the interupt mode from APIC to PIC which, if I understand the manual correctly, seems to be AMIBIOS's version of turning off Plug and Play. Same error. Can anyone tell me what sort of thing is going wrong? Is the smp_lock.h stuff for dual processors? The motherboard I have would support 2 processors, but I only have one installed so don't see why I am in SMP code. Is there something I can do to get CentOS 4 to install? The only thing I can think of I haven't tried is to update the BIOS - mostly because the instructions are not very well translated so I am not completely sure how to use the Dual BIOS feature to roll back if the new BIOS version creates more problems than it solves. Hardware: Motherboard is a Gigabyte GA-7VRXP http://www.gigabyte.com.tw/Products/Motherboard/Products_Spec.aspx?ClassValue=Motherboard&ProductID=1762&ProductName=GA-7VRXP CPU is a single AMD XP2100+ Disk is a normal IDE Maxtor Memory 3 G of DDR SDRAM I can install CentOS 3.8 on this machine just fine, but I would like to move to CentOS 4 because that is what my beefier database machines are running (or will when I get the rest of them upgraded). Thanks for any help folks can give me. -- Cynthia Kiser