Unselectable, unwanted surface

Dear All! I draw a map of a building. After I moved some surfaces of some walls, appeared a new surface above/in the drawing. I can’t select/delete it. Can you help me? Thanks! I didn’t instal the today’s update yet (because I use Rhino in my worplace too, where I need a system admionistrator collegue to do it, but I call one, if it depends on it).
Thankssurface-walls.3dm|attachment (10.9 MB)
Yes, uploding is make a new question. There will be three jpg in this file, but I deleted them before I made a new saving for you, but the file size still big.

If you run SelBadObjects, does Rhino find any?

Thanks. Yes, the SelBadObjects selects the original part of it, but not the surf.

Now try ExtractBadSrf.

My guess is the boundary of the bad surface has a problem so you’re getting a “leaking” render mesh.

Fix or delete the bad surface and the leaking render mesh will go away with it.

Thank you for your help! The ExtractBadSrf made three little vertical line on some corners of the wall. Didn’t happen anything else. The ghost surface remained “untouchable”. I let it go, and draw it again!

If you delete those bad surfaces, the leaking render meshes will go away with them.
Then turn on ShowEdges set for Naked edges, to find the poorly fitting surfaces and fix them.

Thanks for your advices! The SelBadObjects selects the good part of the strange object, but not the bad part. After I extract it, there nothing happened except there appeared three little vertical line. The ghost surface remained untouched. Here I gave up, and redraw the object, Fortunatelly not a big work. I just wanted to write it here. I think when I delete a hole on the object, or when I moved a surface of it, then born the strange surface… Thx again!