Have you checked the sound controls on your computer? Also, the MPEG-2 and AVCHD formats tend to lag on slower systems. More clearly stated, the audio might take a while to "catch up" once the playback is started. If it's a playback problem on your system's default media player, it's probably a codec problem. The included Cyberlink software does not give you the codec free-handedly. Instead, it uses its self-contained miniature "decoder" in order to play video files. Getting interlaced footage to play with Windows Media Player really isn't worth it. Colored lines seem to distort picture with the lack of full quality during playback. Microsoft claims to have a de-interlacing technique in order to handle interlaced video, but seems to not be working or simply having too many side affects. You'll have much better luck if the footage is progressive. The appropriate audio codec for audio playback is the AC3 sound filter - http://www.free-codecs.com/download/ac3_filter.htm.