Here is the fix, those files are bad somehow, I had the same problem.
Go to ftp://24.153.165.234 in your web browser and drill down to:
disk1/share/LS_Pro_Duo/2_usb_model
then download the file lswtgl-3.08.zip
Unzip and run and that will put your drive back at V3.08 and set the password back to password. All data is intact, well mine was.
The Web access window will be in Japanese so to change that log into the NAS and select the second option on the left side and in that page scroll down and in the last 2 fields change the upper one to English and the lower one to CP437.
This worked for me but you are right that there is something wrong with the V3.09 zip files.
Brian