I have used this for a long time with no problems. I went to insert media and it is not recognizing the audio part of some of my MP4's. I have never had this problem in the past. They are all AAC 48khz, stereo. I always have output the same audio settings and have never had an issue before. I have already used the same file with a freebie DVD authoring software with no problem but I like this on much better. Any ideas?