Ok, so i'm pretty confident my system can handle it, but buildings are still disappearing.

For example:
I made a mod with two towers on top of a hill in the 'tundra' area. Had everything set, and tested it. everything works except one little thing:
From a distance, you can see the building, but when you get closer, it disappears. Doors, clutter, furniture, etc, is all still there; just no building.
Loading in and out of the area doesn't seem to work either. I've also tried removing everything but the two towers, but still no luck.

so,
Anyone have an idea as to why it might be doing this?
thanks in advance for any help.

This is a critical bug that we all know about. There is a "fix" but it is not viable because it causes performance issues, and futhermore it just uses low res textures.

Checking "full LOD" is the fix.

ah. thanks. But at least I know now!