Thank you for reporting this issue. Can you post the raw directory listing of the folder containg the empty folder/file? Right click on the folder then select "Raw Directory Listing" from the context menu.
I have never seen a listing with an empty name. I also doubt that no name is a valid name.
It definitely is not a valid name at all. As you're probably aware from my other post today, I use a custom FTP daemon that I developed myself (for dealing w/ encrypted files). It had a bug and was outputting a null directory name, which didn't crash other FTP clients so I never noticed, but does crash SmartFTP. I have fixed the bug in my daemon, so it is no longer an issue for me, but just thought I would point out the bug so you could code some protection into SmartFTP (if desired) just in case anyone else ever had this issue (the fewer possible causes of crashes the better, right?).
The dirlist was completely normal except lacked any text at all for the directory name. Should be fairly easy to replicate if you want to fix it, although as you mentioned, as its not a valid dir name I doubt this is a common issue.