Umm, first thanks for replying, but....90% of what you just said went over my head. I've tried reading it multiple times, and figure out what I did wrong....As far as I gather from what you said, any hole in my mesh, even if it's put there, will be 'filled' and treated like a solid object. Which..Isn't what's going on.....
Let me try explaining it another way; My mesh is broken. Walls/Faces are being treated as if they don't exist, other walls are being loaded, but have no collision, and there's places in this house that randomly have collision, and others that simply shouldn't. One big block is in the dead center of this house, and it's consistant with the block that Blender inexplicibly forces you to load every time you start a new project/mesh, which was deleted from the start. Other parts are consistant with edges/faces that were also deleted, but are still registering as 'present' when loaded into SL.
The door I can explain away as something is registering as being in front of it, but windows and the deck randomly have collision in some areas, and none at all in others. What I need to know is if there's a way to detect these invisible walls and collision zones or not, and fix them.