ACPI Error

[Shellness]

I am running CentOS 5.1 on a mini-ITX. The box is set-up with ACPI Enabled at S3 and set to wake-up in the morning with ?Resume by RTC Alarm?.

Occasionally CentOs fails to complete the boot, typically after a power failure (ordinarily the system closes down at night under a Cron command). After the ITX has self-started, the screen shows the green CentOS page with ?Booting Linux?; a split second after this the boot hangs at ?ACPI Core Revision: 20060707?. The last time this occurred I fiddled around with lots of settings and, even though I had reset everything to the original settings, somehow booted CentOS fine. If I disable ACPI the boot is fine but I lose the morning self-start.

Has anyone any ideas of what I need to do to resolve this, please?