it is extemely difficult to fault find this sort of thing at long distance without exact information.
It may be something is corrupted from a communication interuption. You should never interupt communication, only by the cancel command, and leave a few seconds between unplugging and replugging the usb connection.
Follow the instructions in the leaflet for uninstall on page 6 EXACTLY. Remove the Panasonic usb driver from device manager with everything connected. Then disconnect and reboot.
The applications should be removed from Control Panel, Add/remove programs. Reboot.
Now try installing from scratch.
If the driver has become corrupted it is more complicated. Depending on your version of windows, after having performed all of the the above again, search for the files in the root of the installation cd, ma*.*, and manually delete them from windows/inf, and windows/system. Do not attempt this if uncertain about any procedure. Reboot and install from the beginning.
again, it is very difficult to be specific at long distance without seeing the fault. When transferring songs, which come up on the sequencer screen, I forgot to exit to the home screen many times for the next file, and just carried on from the same error message, so this should not happen unless maybe communication was interupted somehow.