The lord of the rings 2 trying to convert in a cople of way's

Now please listen up,
I have to different Lord of the rings 2 movie's. One is in 3 postx parts. And theother is in two parts xvid vite. Now the postx movie is good quality video but bad sound(really bad). The xvid vite movie is good quality video and audio. So I tried to encode the xvid vite movie but this one has an bad framepart on 8 min. When I play it in any player (does'nt matter) on 8 min it will stop end I get a Windows xp error message and i have to close my player. So this happen too when tmpegenc reach the 8 min part. So what do I have to do I tried avifixed already. I also tried to join the both movies in 2 large avi files. This works on the postx movie but not on the xvid vite, i get the different sampling rate error when i try to ad the second part. I want to do this beacause when I have the postx movie and the xvid vite movie in 2 large files. I can use the xvid vite movie as audio source and the postx movie as video source in tmpgenc. Is this possible. Can anybody please help me. What do I have to do to encode this movie?????

 

Yes but the postx this time has really bad sound. So I have to use the audio of the xvid vite movie. But it's still in two parts. I want it in one part. How virtualdub gives me the different sampling rates error. Is there maybe a way to just rip rhe audio from both files. And then merge that audio files together. If that work's it's also fine. But I still don't understand why I can't frameserve just this single movie. All other can. And if I just load this single movie directly to tmgenc it loads just good.