Getting Soundtrack Off A Dvd, How to perfectly extract a 90-min track? Options

Hi guys -

I tried to rip the audio off a music DVD. The DVD is 90-min long.

I did use bd4go in order to convert the extracted PCM file to 44.1Khz WAV file (because I just can't convert 48Khz AIFF to 44.1khz AIFF ???!?).

I opened the about-1-MB extracted file (so 44.1Khz WAV) in Peak 3, and I noticed that there are some glitches at times, either on one channel or on both channels, and that some parts of the music repeat.

How can I get a perfect extraction?

I'm using a 500Mhz iBook.
It's the first time I'm having problems extracting a long DVD soundtrack.
Can someone help me please?
Cheers.