Acpi\smo8800\1 <Firefox>

When the sensor detects that the laptop is in free fall (e.g., being knocked off a table) or experiencing an extreme shock, it sends an interrupt signal to the system. The corresponding software driver then issues a command to the HDD to execute an of the read/write heads. This retracts the heads from the platter surface to a landing zone, preventing head-to-platter contact (a head crash) which would result in data loss or drive failure.