too big?

[HellSpawn]

Hello everybody!I recently encoded Stephen King's Rose Red and I had a little problem.Let me tell you that the movie is HUGE (5 and a half hours) and comes in two dvds.I decided to encode each dvd separately.I encoded the video and then multiplexed it with the ac3 sound.When I tried to playback the result everything was o.k. until I moved the player's slider.Then the audio got completely messed up and if I moved the slider again I got a "format not supported" from the player.However I tried to cut the avi and all of a sudden each piece sounded perfect.
Note that the final avi's size was about 2.1 Gb(with the sound).However I am using Windows XP with NTFS file system.So what was that all about?:confused:

Thanks a lot!