I not always recieve error message. Usually SV just stops working and windows error pops up or vegas just closes itself without any warrning in a middle of rendering. I recorded everything on 30 fps and try to render it with 1280x720 6M .wmv. I use Vegas Pro 8. And yes i did use multiply layers and that's what i think causes the problem. I have 7 layers but i had 8, deleted one.
I will try your advices. I think this might be this RAM thing. I have set 128 out of 1024 possible. Will try 900 this time.