Smartftp transfers 0k files

Hello: I have 3 copies of SmartFTP running in remote offices that transfer files to our main office. I also have a copy running in our main office that transfers files outbound. all of these copies have a problem in that from time to time the transfer will record a 0k file in the target when the source file is not corrupt or in use. What causes 0k file transfers and how do you prevent this? The problem is not related to OS or local system configurations as it happens accross winXP. win2000, win2003 server.

Please try to reproduce the problem. Then post the log from the transfer. To get it double click the file in the transfer queue.