Well I've got mine to work eventually.
I had originally setup a user account when I installed the windows software. This user account was added to the allowed users list in the NAS Frontview. I've never been able to access the NAS through this account. I've tried sending out email invites to myself, but none of the arrived. Through this account the tray icon always logged itself in, went blue and told me that my user was logged in. But whenever I clicked connect to NAS all got was a windows explorer window showing 'This Folder is Empty'.
Today I sent myself an email request through Frontview at an alternative email address and received that email shortly after. Following the link in that email to create a new account, I've done so with a new username and at the first attempt at logging in with that username I have immediate access to my ReadyNAS!! Woohoo!
Now I'm happy that it's working, but there's a nagging frustration in the back of my mind as to what happened with the first account. It seems there is some issue with the way the user is created that the NAS doesn't like. Hopefully this can be sorted, as I had followed all the instructions during installation, probably along with the others having similar problems.
Anyway, I'm finally up and running and able to access the files.