The Archieve invalidation most of the times only need to be activated if you replace something big like a body patch : Breezes and others requires to deactivate Archieve Invalidation and activate it again , most of the times you don't need to worry about it since FNV is not as picky as Fallout 3 was , but like i said just keep it activated at all times using NMM or FOMM. Also , Archieve Invalidation sometimes can work differently depending on your FNV version so i suggest you don't mess around with it too much .