This symptom is due to the limitations of the current specifications that no signal sound is produced when a floppy disk drive is connected to the multi-purpose bay.
A PCG-XR series VAIO computer produces a signal sound when the system starts up or a device is connected to or disconnected from the multi-purpose bay in the default state. When it returns from the power saving mode (hibernation), it checks the drive in the multi-purpose bay in order to support the exchange of a device of the multi-purpose bay in the power saving mode. When the checking is done, the system produces a signal sound to start Windows. The checking of the device takes about 30 seconds.