Audio synch problem in clip view

[mcope1961]

As I approached getting a project up to and past 10 minutes in length, I noticed that when watching clips in the clip view that the audio was out of synch with the picture. If I switch over to the project view, there is no synchronization problem. If I go back and look at clips at the beginning of the project, those clips are in synch. So while I don't think this is a disaster, what's happening and is there a way to keep my clip views in synch as the project grows?

As a side note, I also noticed there is more pixelation when watching clips than is normal with the project view. Is there a preference I need to adjust?

Let me also add that I'm editing an mpeg2 video file. Could this be a codec problem and/or a mpeg2 problem?