Your FTP software must be wsftp to find WS_FTP.LOG in your folders. I use the same software. You might want to turn off the log feature in wsftp. I use this myself and it caused problems with the .log file for the captcha feature.
The log feature in wsftp creates a .log file to track FTP uploads and downloads. I would advise that you view your folders and delete them.

Blue Man Group
There is no such thing as stupid questions. Just stupid answers