I have a Toshiba Satellite A665D-S6059 with the same problem using an update from 10.04 to the final 10.10. Another curious fact is that when it boots (with acpi=off) the machine will shutdown when requested, but will not turn off without pressing the power button. The first restart then fails, even with acpi=off, but will reboot with the second restart. I did not see this behavior with 10.04 version.
I have a Toshiba Satellite A665D-S6059 with the same problem using an update from 10.04 to the final 10.10. Another curious fact is that when it boots (with acpi=off) the machine will shutdown when requested, but will not turn off without pressing the power button. The first restart then fails, even with acpi=off, but will reboot with the second restart. I did not see this behavior with 10.04 version.