Hi!
Decided in mid-3ds Max mode to follow a From The Basics blender tutorial series (youtube.Ryan King Art’s multi-part tute about the house and interface both). Found with a little practice that blender’s not as terrifyingly deadly as I thought it was. Determined to make it work.
My problem: I’ve taken a cube, looped it, added a mirror modifier to it for symmetry, and can get the base house modeled without (too much) difficulty. Next step in the tutorial is to add a new cube for processing as a chimney. However, every new cube (or anything else) added to the base house comes in as a PART of the existing house object, then inheriting the mirror modifier (tried deleting the mirror modifier and half the house disappeared, my first clue that Something Was Wrong). I cannot seem to DE-select that initial house object; EVERYTHING I add to the workspace (or even a couple of events of duplicating various parts) gets mirrored as well.
I can’t seem to find a way to de-select that initial house object. Feller in the tutorial isn’t having thing problem, but neither does he (in an otherwise great tutorial) address the possibility of what’s happening. My blender seems determined to carve out its own little pocket dimension. 
Any of this seem familiar to the blender.old hands? I know I’m missing something basic or doing something stupid, but I haven’t a clue what. (The Max modeler in me knows ways to still get the job done in blender, but they involve a great deal more Ahead Planning than this tutorial is calling for.)
Many thanks!
Davey