Vegas render audio error.

hi guys, i just finished rendering my new project, but i had got a little problem.
the fact is that the first frame of the video, freezes and the audio continues reproducing. So the sound does not cordinate with the video.
it is clear ?
i'm form argentina, and my english, is not perfect, be patient.

what's the render output format? settings? non-native Vegas plugins?!
more details please :)