The first problem is most likely a slightly unbalanced DVD. Some players are just more susceptible to it than others.
The second problems most likely occurs when the DVD switches layers. The LOTR DVDs are very full and use multi-layer technology to fit everything onto them. The pause occurs when the laser adjusts its focus to a differnt layer. Players will act differently during this transition. Some more expensive ones will barely even hiccup. Others will have longer pauses that seem like skipping. Mine does this, too.
