GL,
For the first post where the attachment wasn't appearing, I have verified that the file exists, so I'm not sure why it's not appearing. As far as I can tell, the link looks the same as the post where the image is appearing, so I'm not sure what the difference is.
My next thought was to compare to
http://forum.daysailer.org to see if the problem exists on the current board, but when I pointed my browser there, I found that our account is suspended!

I've emailed Craig to see if he can get is sorted out. I'm hoping we can get that sorted out quickly.
My thought process is that if these issues exist on the current forum, then I'm not going to worry too much about it. If they don't, then I will work on diagnosing and fixing. My main goal is to make sure we have equivalent functionality to the current site before we cut over.
My biggest concern was making sure that email was working. Glad you were able to confirm that as well. As I stated in my email, I was able to confirm that the basic account registration functions all worked and sent the expected emails out.
Thanks,
Richard