Two things to try
1) Make sure the system date is set correctly
2) Manually add a firewall exception for PDapp.exe
C:\Program Files (x86)\Common Files\Adobe\OOBE\PDApp\core\PDapp.exe
Just uses standard port 80 and TCP/IP
Thanks Dave, the system date is OK and I've added a firewall exclusion for PDapp.exe but AAM still fails.
(The Norton 360 security log shows the app successfully accessing the network).