I got a ReadyNAS Duo for Christmas with which I am gettingI am getting exactly the same issue (win 7 64). The installer causes a windows dialog to popup saying the the installer has stopped working. Clicking ok on the dialog appears to allow the installer to finish however the initialisation failed error code -3 comes up when I try to start ready nas remote. I also tried to install the leaf networks client but the same thing happens. I get an error code -3. I was able to install on my work PC which is also win 7 64. the only major difference I can think of is that this laptop has VMWare workstation installed which means there are already some virtual network interfaces created for it (no idea why that would be a problem though).
Steve Pavett - RNDuo@home - RN316@work