You have to provide system info, details about your render and comp settings and so on. Also check the file in a player other than VLC.
Thanks for response! It's not the player's problem (it's mpc btw), I import it into Premiere for post editing and it's disaster to see the failed rendering.
Mmm need time/Everest to find out the system info. Generally render setting is just straightforward AVI lossless/best quality with no codec assigned.