[Closed] Video Rendering Issues

I'm having some problems rendering a video on Sony Vegas Pro 9. When I select 'Render video' it no longer gives me the option of rendering in '.wmv' format. So instead I have tried to render the video in a .avi format. It begins to render but seconds into the render, it comes up with the error message of 'The system is low on memory' and stops the render, it says close applications to help improve it... but they're all closed anyway.

Now why wont it let me render these videos!? It has always worked previously (albeit very slowly) without too much trouble and with the same camera, so why would it be any different now...?