What are these black lines?

[gardendiva]

Can someone tell me what the black lines are in this picture of my floor plan? I noticed a couple of them when I pulled the view back in floor plan, but now they're multiplying. I saved my work, thinking it might be some kind of Windows issue, but upon opening again....there they were.

I can't select them and can't seem to find anything in the Help menu regarding black outlines.

Thanks!