Jittery Playback

[AndyMB]

Bit of a strange one here, I've noticed that during some adverts there is often a slight glitch every few seconds or so, this never happens during the main programme...until now.

I recorded the first episode of the new David Attenborough programme in HD and the panning shots were very jerky indeed, almost like watching a 1080p film on a normal computer monitor, I've never experienced this before..any ideas?

Thanks

Andy