Most modern computers use a power management and configuration method called ACPI (advanced configuration and power interface), which helps prevent resource conflicts but which also limits the amount of tinkering you can do with manual resource assignments. If you get a message that a particular resource can't be changed, or if the Use Automatic Settings check box is unavailable, it's probably because of ACPI.
To see what prompted a machine to wake up from power hibernation at the cmd prompt enter:
powercfg /lastwake