WD My Book Live Duo - Error 0x8007003A when copying files?

Have a new WD MBLD and separate (Buffalo) HD connected via USB and want to copy the files from one HD to the other. Can see the buffalo HD drive and see files on it but when trying to copy I get an error preventing me copying… have successfully copied files from laptop via network (wireless) but this is slow and I have a lot of files on the HD that I now want on the network drive so can anyone please help???

Running Windows Vista Ultimate 32 bit

It is not possible to copy files from the USB into the My Book directly, you can connect the external hard drive directly to the PC or connect the USB drive to the My Book Live Duo and map it to your computer. You can check page 123 of the manual for more information.