I had a similar experience as well. I would get blank images or blank frames in animations. The project I was using that model for was 100,000 SQ FT office building with the site and surrounding topography. I tried turning off the mesh, but it didnt help at all. What did help was reducing the amount of entourage that was in the model (trees, cars, etc.). Basically I had to render it bare - without any foliage. I still have no idea how to get it to render with everything in the model. We did this on a brand spankin' new computer we just bought too - so I know its not a computer limitation.
I'm not sure if you are familiar with Piranesi, but that was my solution for still images. Render the model without entourage to a Piranesi file and then insert trees, people, cars etc. in there. It worked out pretty nice, IMHO.
Hope this helps.
RA 2012 x64, Piranesi 6 Pro, Sketchup 8, Windows 7 Pro x64, Intel Core i7, 10GB RAM, ATI Radeon Mobile 5870