That's a Sky issue - nothing to do with the films (the Indiana Jones HD transfers shown on Sky are superb). It could either have been because the weather or another factor messed with your signal, or because you were watching an HD recording at the same time as recording two other shows - the earlier Sky HD boxes did have problems with that, causing playback problems as you describe.
And a final point - older films have every ability to look (and in many cases sound) as good if not better than modern movies, as film stock is higher resolution than current HD standard. The quality of what you see depends on how much work was done mastering the HD version you see on TV/Blu-ray from that original, high-resolution film print, rather than from an earlier copy or digital downmix.