I just got my first imac after using Windows since before it was born. 
Have been successfully using Calibre/Alf and Nook for PC and Study on my now-old PC for over 5 years.  I have d/l'd and tried Nook for Mac/Study from any place I could find it and none will connect to B&N from the mac citing "
We are experiencing an issue while attempting to connect to the time servers. This may be a result of your network's firewall settings".  NOT!!  The firewall isn't even turned on.  The Nook readers are still working on the PC so I  can't figure out WHY they wouldn't work on the mac.
Any ideas?
Thanks!