AE sound error

hi, Im having this error in the pic…dont know why is happening and thought maybe one of u guys know something or had this problem before, it happens when I do the RAM preview, I cant do it! but if I turn the sound button off it works but obviously without sound.

When I try to export the movie in any format it only exports like the first 20 seconds and then bam! the error screen again.

Any posible ideas?

thanks!

I cant add pics :confused: heres the pic: www.framecreation.com/error.gif