Actually, I found a cure for the problem. It was just a matter of saving the model and then reopening it. Still, it would be interesting to know why it happened in the first place, but I don't have it anymore to do a screen shot.

I created a fence post as a group and then duplicated it for the entire fence. For some reason, white duplicates of the fence post appeared near each of my posts and they can't be erased. I would appreciate any advice as to how to erase/avoid these in the future.

Thanks, mitcorb, for the advice. I followed your algorithm but, as it happened, it didn't work. However, I tried again; this time, following your algorithm and then rebooting the Mac. It worked!

Hopefully, this may be useful to some other benighted soul.

For some reason, when I try to change my smoove tool radius, it is locked at a fixed dimension and will not change. It worked fine all year, but now is frozen at the weird dimension, 5'8".

Is there a way to reset it or some other strategy that will free it up?