Camera is not switched on or not switched to transfer mode. Switch on camera and set the camera to transfer mode.
DiMAGE 7 Series only: You have to confirm the transfer mode with four- way controller.
Otherwise the USB chipset driver has to be updated. Contact the manufacturer of the mainboard or the manufacturer of the USB chipset.
Only for Windows 98/98SE a USB driver (from software CD-ROM) has to be installed before.