This is a little counter-intuitive.
When it says to "select Allow computer to turn off this device" does it mean to check it or not to check it? By checking it, you are, in effect, turning /on/ power management rather than turning it off. Maybe it means to navigate to the power management screen, go to "Allow computer to turn off this device" and deselect, that is, uncheck it. RIM's help screen is very confusing.
IOW, for the purpose of upgrading the BB OS and avoiding the problem of the BB not connecting to the ROM (a problem I've had on iMac computers running Windows on virtual machines), should the Allow box be checked or unchecked? A simple question, no?