Hi... I'm having some troubles encoding a MPEG to MP4 format...

Well... the MPEG was recorded using WinVDR Pro and when I play it, everything sounds good with no problems. But when I convert it to MP4 (x264 and faac codecs) the audio desynchronizes in the middle of the playtime

Well, I used the following tools

Avidemux - It was my first choice
Mencoder - The second choice

I demuxed the video file and the duration of both video and audio streams are almost the same, with about 0,043 miliseconds of difference between both.

So I ask: Any thoughts?