Low Memory when rendering a video file (Win 8.1; HP Envy 700-230qe)

Rendering a 4-minute video (with several video tracks) using Sony Vegas Pro13, keeps stopping around 70-80% of completion --- saying that there's low memory.  

How could that happen on a HP Envy 700-230qe with 32GB DDR3 memory?

I look at the Task Manager:  the  "Commited" memory keeps increasing during the rendering until it hits the full number (36 GB in my case)  and then the memory is depleted, which stops the render.  


(No changes to the system except addition of an SSD drive as main drive, and a Blu-ray burner)