Norton Ghost 15 Fails Regularly because of iTunes, and is Slow

Ghost 15 incremental data backup fails every time I have synchronised more than one device with iTunes.  This happens, even if I subsequently close iTunes down before running Ghost 15.  This is very frustrating as it means that most scheduled evening backups fail.  Can someone please point me in the direction of a cause and preferably a solution.  Thank you.

 

Also, I back up just my data, incrementally, (about 73 Gb) daily, to my WD External Drive.  Ghost 15 takes over an hour each time.  Can anyone tell me if this is reasonable please?  It seems overly slow to me, given that it's incremental.