The high valley walls of my landscape looked a little bland so I decided to add some of those huge cliff pieces, I did this for one world space without any problems but for the 2nd I can only perform as little is 3 or 4 operations in the render window and it's CTD.

I had already taken out the Hires texture pack and I can see when it crashes that it's only taking up as little as 0.4 GB and I'm using a 4GB enabled version, the memory load on each cell is only around 5% so what the hell is going on???

I've checked the esp in FNVEdit with no problems and can run around in the world space with the game pretty stable, I'm at a loss.