Ok, I have just moved an entire city into its own world, made a couple of meshes, put in the teleport door. A few hours ago I cleaned out some useless textures and so forth. In the CS all the models have textures attached so nothing missing there. I enter the new city world, walk half way through it, the computer goes to load an area as per usual and CTD.

So I remove some meshes and run it again. No CTD. Ok so its those meshes me thinks. So I put them back in order to start taking them out one by one to work out which is the baddie. And the game works fine. No CTD, I walk around the city, all loads up, all is ok. No CTD. Whats all that about then?

Sometimes the game CTD's for no apparent reason. Did it happen more than once before you deleted the meshes?

Nope, just did a back flip and landed flat on its back on that single occasion. All was going fine, I walked through a seperate world city space, the game paused momentarily (as it always does) to load the next area, blink and you miss it kind of usual pause, and bonk! up comes the error message saying Oblivion has to close.