I updated my KMPlayer recently to version 126.96.36.199 and noticed the audio would immediately go out of sync when playing .AVI files. Follow the instructions below to fix.
Launch KMPlayer and go to preferences. F2 or Right Click > Options > Preferences.
Then select “Source Filter.”
Then change Normal AVI: and Damaged AVI: to say System Default.
Hit close and you should be good to go!
I know this hasn’t worked for everyone. If it doesn’t work, I would simply recommend going back to a more stable version until they get the kinks worked out. Version 188.8.131.52 is very stable and doesn’t have any syncing issues with the audio. You can download the older versions here.