Built in AntiVirus is a MESS

I have an RN104 purchased at the beginning of november so it's relatively new (firmware 6.1.4), and it's my first foray into NAS so didn't appreciate these things had processors and what they were entirely capable of (if they have the power). Initially I copied every thing over from the various external HD's I had connected to my HTPC before playing around with it and setting up antivirus, then last week I realised I had a lot of mp3's (a hundred or so) still on my laptop, stuff I'd downloaded more recently, and figured I should move them onto the NAS, however after a while it would fail and I discovered the NAS had locked up, so rebooted, tried again and again it failed, third attempt made go hunting for a reason on the net where I read about problems with the antivirus, so disabled it and finished off the move without any problems. I re-enabled the antivirus and thought well maybe it was to do with the number of files I was copying at the time.

Then earlier this week I was moving a Bluray rip onto it thinking it would be fine, not so many, a rather large mkv and supporting nfo/backdrop images, however it did the same again, several attempts failing before disabling antivirus and have left it disabled.

Now there is the possibility that some of these are large, even the mp3's (being dj mixes over an hour long), but even so I wouldn't consider them that large in this day an age, so clearly the antivirus isn't fit for purpose in what we'd expect to be normal use.