> During boot with acpi=off
Bad idea, except as a debugging aid.

I completely agree. Without acpi=off, the system does not boot at all, see bug 689420.


> The full dmesg output is attached.
The attachment seems to be missing. **Please also attach "acpidump" output.

Sorry.
Alas, the output of dmesg is not 100% reproducible: on this boot no BUG message occurred.
Now I have attached an old log from /var/log/dmesg.2.gz with BUG.
I'll try acpidump in the next e-mail.