Tried sketch rendering with half of my layers swithed off and then the other, one worked the other didn't however the one that worked didn't have nearly as much work to do.
Then I tried switching off trees and the site mesh, this resulted in the rendering bar getting further, but ultimately it failed only this time I got the message "error in analytic shading method error code - 108 (not enough room in heap zone) any
I had extended my virtual memory to 2gb but I will give it a go at 4gb and post my results.
Can trees and site meshes (200m x 500m in size) be to large a file to render sometimes?
cheers.
Mark.