Media via Macbook Mirroring not working!

Up until now my Apple TV (Third Generation) has been working like a charm.
However, a problem arose today when I was using the mirrroring option on my 2012 Macbook Pro. Mirroring was working fine up until I tried to play any sort of media, whether it be a song on iTunes or a video online.

The video or audio in question would play for about two seconds (with no audio) and then stop playing all-together, for example the online video would stop at 2 seconds, and despite the fact that the video had buffered completely, would not play any further.

As soon as I stopped mirroring, the media worked absolutely fine on the computer, so it is definately a problem with the relationship with the Apple TV.

Previously this had all worked fine, so I am not sure why all of a sudden it has stopped working. All other aspects of the Apple TV are working fine.

Any suggestons/advice would be great thanks.