Login free for ReadyNAS Duo?

I can access files on my ReadyNAS Duo from all the PCs on my home network but each time I reboot a PC and try to access files on the ReadyNAS via Windows Explorer it demands a user id and password. Once these are entered I can access files fine until I reboot the PC again. Is there any way I can avoid the initial demand for a user id and password? I have tried all the options that seem relevant on Frontview so maybe this can't be done. Is there any way round this or is it always necessary to give a valid user id and password on PC startup?

I expect there's a posting on this somewhere but I can't face trawling through the thousands of posts.