I've had problem uploading with WS_FTP before, too. The problem arose when I tried upload by draging from the file explorer to the remote window in WS_FTP rather than navigating to the file in the local side of WS_FTP and using their stupid arrow up button. It worked fine when I did it WS_FTP's way but not the drag'n'drop way. I'm not sure if that's what you're actually doing - but at least it's something.

- trs