I am running NAV 2013 , WIn8 Pro 64bit.
A few days back I inserted a pen drive and saw only shortcuts to the folders present on it instead of the folders themselves.Also an autorun.inf file was sitting on the drive which contained random nonsense. NAV didnt detect anything by itself or during the right click scan of the drive.I soon found that 6464.js and 35.js had been added to the startup ,disbled and deleted it.(they sprang back in place automatically).I even submitted the files to Symantec for analysis.(Tracking #28515169) and found no solace.I then had to uninstal norton, install Kaspersky AV 2013 to find out I was infected with Trojan.Win32.scar.a.(An exe was running in the background which wasnt seen in task manager).
I find KAV to be slightly heavy on resources for my taste. So , all I am saying is just ADD the goddam definitions to the database so I can keep using NAV.