When i transfer a video file about 700mb on the timeline the audio is off timed with the video. How do i sync it? When i render it it has the off timed audio, still. The audio on the original file is fine, just when it comes into contact with vegas its off timed.

my specs:
Vegas 4.0
2.4ghz pentium 4
512 mb
100+ gig

other projects i rendered are fine, shorter ones anyway(less than an hour ones but this project is 2 hours).