Constant errors with Ghost 15.0 backing up across network to NAS

Hi, I'm trying to use Ghost 15.0 to back up across a network to a Netgear Stora NAS device. I have an apple Airport Extreme Base Station router. I have a windows XP and a Windows 7 machine. Backups keep failing with these error messages:

 

 Error E7D1001F: Unable to write to file.
Error EBAB03F1: Error performing inpage operation.
Error E7D10046: Unable to set file size.
Error EBAB03F1: The specified network name is no longer available

 

I've trawled the forum and Google and tried most suggestions (network throttling, using IP address instead of drive names etc etc ). Nothing works.

 

Windows backup works fine so I know the network can take large volumes of data.

 

Any suggestions? I'm desperate and will have to drop Symantec for something else if I can't get it to work.