Sound problem

I am creating a clip from clips scripts taken from a DVD. I made them with mplayer with sound in pcm@48khtz (so kdenlive could handle it). When I play these separate clips in mplayer, they sound (and look) perfectly. When I use them in kdenlive, the sound is a bit "breaky". It sounds like a short gap every x tenths of second. I first thought that it was because the processor wasn't able to keep up with the CPU required to present the monitor (either clip or timeline). But then when I export the movie to DV, I noticed that the sound breaks are there as well. How can I keep that from happening?