Asynchronous picture and sound means that the video and audio portions of your video file become increasingly out of sync as the video plays.
This type of problem is usually caused by errors in the source material.
If your source material consists of MPEG files, you can perform a more detailed import of the material by generating a new frame table.
Then, check to see if the picture and sound are still out of sync.
You can also try to resolve problems with asynchronous picture and sound by using the audio/video offset feature.
To do this, right-click the video object in the track view and select "Audio/Video Offset" from the context menu.