I add my video file to WMM and start editing along just fine. Video is fine and sound is normal. Being a mom I usually have to walk away from the computer at some point for a bit but come back to the video playing but the sound was gone. There was only this very annoying popping and crackling sound. It was just working !! I have closed WMM, took the SD card out and back in, restarted the comp <-- which worked to fix the problem a few times.