I just installed CentOS 4.6 (because I had 4.6 media handy) on a new system, which has a SuperMicro PDSMi mobo with an E4600 CPU. I then did yum update to get to 4.7, although I don't think that's relevant to my query. I wondered why "shutdown -h" would not power down the system. I then also discovered that the soft power button did not initiate a switch to runlevel 0 to do a controlled shutdown. When I looked in grub.conf, I discovered that the installer had included the boot parameters "noapic acpi=off". I removed them and rebooted, and then found that both soft shutdown from the power button and the final poweroff worked fine. I haven't stressed the system yet, but it seems to boot and run fine. My question is (at last): why did the installer decide it necessary to include "noapic acpi=off"? Previous installs of CentOS on other hardware have not done that. Cheers Tony -- Tony Mountifield Work: tony at softins.co.uk - http://www.softins.co.uk Play: tony at mountifield.org - http://tony.mountifield.org