http://i52.photobucket.com/albums/g8/Nureese/BlackFogDistanceBlotch.jpg

At first, I was quick to blame Respawning Varla and Welkynd Stones by Khettienna. I noticed the issue shortly after loading into an Ayleid dungeon and looking down a long tunnel of rotating blades where the end held some fog and a dark area behind it. It was clear that it wasn't Khettienna's mod, as I had smuggled in a few other small mods before this blotch distance showed itself. Recently it was prompt hacks to prevent confirmation screens and quantity prompts for buying from merchants.

As you can see, the problem shows when there is a long distance involving darkness and ambient glowing fog. This might be related to the broken nightvision effect.

I am using OBGE v2 with:

NormalFilterAA.fx
Ring_SSAO.fx
Pseudo_Bokeh_DoF.fx
Godrays.fx

Other large mods are Race Balancing Project, L.A.M.E., and Integration - the Stranded Light. I need an hour to think of what other mods where recent before I begin the one by one shuffle.
Perhaps this is already known and there is a fix for later. This is where my post stops because I took two Ambien and have to sleep now. And OOO 1.33.

This looks like there is no ambient fog (not to be mistaken with the particle effect fog). At a certain distance (usually 3000 units) there is a clip distance setting at which geometry is not rendered anymore. It's covered by ambient fog so you can't see it, but if there is no fog it would look like on your screenshot. No idea why the fog isn't applied anymore in your game under certain circumstances though. Could be a problem with OBGE or the nighteye shader or it could be a problem with mods that change the dungeon light settings (including fog color/distance).

Thanks for responding! Yes, it could have been the night-eye shader. It looked like a lot of black with other 8 bit colors mixed in. I'd like to show you a pic that night-eye in my game, but now everything is back to normal for no good or bad reason. I returned to Vilverin, where I noticed it first but now everything renders properly and night-eye looks as it should, instead of the flickering black screen and 8 bit colors it used to be. I cannot think of anything I did differently because I have not done anything except addi high res welkyndstone textures to the welkynd stones via OMOD archive.