I am trying to back my Cisco Firewalls and most of them are doing fine and complets the backup in a few seconds 

but i have around 5 FWs that do not complet 5520/5510/5505 all are runing same version and i have managed to back about 13 FWs before them they dont seem to fail as i am wrighting this they have treid to backed for about 2 hours.

Any ides?