I hit this problem with Skyrim but I'm also getting it in FONV. I've placed a Deathclaw in my 1st cell and when I'm in a few other cells connected to it (even one separated by a cell) I get a ghost noise of the Deathclaw breathing, like it's still loaded and active (maybe a similar cell co-ordinate for the Deathclaw). Does anyone know what causes this and better yet how to stop it?