Does anyone else have this SLIGHT problem? Okay, I was always wondering why I would crash upon exiting my game, so I took a few hours off and tested which mod caused it. Turns out, it is New Roads and Bridges. Anybody else have this SLIGHT problem?
What you probably have is a mod somewhere in your list that deletes a vanilla item. Could be a rock, a bush, a tree, or whatever. By itself, not usually an issue. NRB4 comes along and moves that rock, bush, tree, or whatever. The record is no longer deleted. The crash is caused because the game is unwinding data at exit, and gets to the affected record, but then crashes because elsewhere it had the record marked as deleted and so the memory space held by it isn't valid. Boom.
You either need to go through your load order using TES4Edit to find the mod that's deleting something then run the undelete on it, or just go grab Fast Exit 2 from Nexus and never deal with the hassles of exit crashes again. Or even LONG delays at exit.