Sony Vegas rendering problems

Hello,

Recently i have started recording gameplay from my xbox in 720p ( from a HD PVR) and recording short commentaries to put over the top and have attempted to use sony vegas pro 11 to render my video.( the video is about 6 minutes long)

When i come to render my project the time it will take just keeps rising and rising, i left my laptop and returned ro find it would take over a day to render my video and the time was still climbing! I have tried many different templates and ways to try and speed up rendering but nothing seems to work.Is there any reason why a 6 min file is taking this long to render?

Any help would be massively appreciated :)