Maybe the problem attachment was partially uploaded, and then aborted when it exceeded whatever the requirement was. But the partial upload remained in the forum database as a file with the filename. That would explain why it couldn't be sent again, at least with the same name. And being partial, couldn't be shown. That's just a guess.
The tailstock was just a random image I had once downloaded. I sometimes do that for lathes and bits that I think look good, for future ideas.
I hope problem is solved, if not let me know.