Is it any particular channel? Ive noticed the FTA's are running over schedule much more lately. I've got the MYSky to add 2 mins extra at the end of every show. But have had to extend by 20 mins shows like Frozen Planet else I'll still miss some 5+ mins of show. You'll note the red button on the Planner will extend recording by 20 mins for that particular show. Careful if you record two shows at the same time followed by 2 shows immediately afterwards - you'll get record failures and cut-offs. Tuner cant handle recording 4 shows simultaneously when one takes into account extending etc.
Its poor programming when a show runs over its alloted time. CBS with CSI Miami on a Sunday night used to do my head in - the live sport made the schedule run some 30-45 mins late EVERY week. Had to record the show afterwards as well to ensure that all of Miami recorded. Some PVR's/cable providers just arent smart enough to handle such broadcaster variances.