Rebex FTP 2.0.0.7 is more than 6 years old. Although it looks like the problem might be caused by something else, using a more up-to-date release is greatly recommended because of the new logging capabilities that can be used to learn what is going on. Would it be possible to try connecting with the current version, use its LogWriter property to create a communication log (see rebex.net/kb/logging.aspx, but use Verbose instead of Debug) and mail it to support@rebex.net for analysis? We should then be able to tell what is going on!