Hello, We have a number of systems running KM400 chipsets from VIA (Socket A/462). Two different models have produced the same results -- DFI KM400-MLV and MSI KM4M-V. When a /sbin/reboot or /sbin/shutdown -r now is issued, the system does everything you would expect from a reboot, but when it gets to Rebooting System, it hangs and requires a power cycle. The logs do not indicate anything is going wrong. It's not a kernel panic. I've tried appending "acpi=off noapic" or just "apci=off" to grub.conf and neither help. We've tested these boards extensively with various CPU's, hard drives, and RAM and they show no other issues, so it's not hardware defects or hardware compatibility issues. I'm not sure what is going on, but assistance would be greatly appreciated. Thanks.