Just recently I've noticed an occasional pic glitch on bt-tv, or via the NOW BT app, either that or just a spark glitch sound, can happen on live TV too.
The tv is LG42LK45OU
I've reset the tv settings from 1080p to 720p to see if this helps.
It's a recent new box so unsure why this occurs?
I saw that the sound settings were at Surround for S/PDIF, I've changed this to Stereo as we don't have a surround sound TV.
I've put the picture setting back to 1080p and will check this.