Up- and download problems, version SmartFTP version 1.5.988

I have since a few days (after the latest update to this SmartFTP version 1.5.988) problems with up-loading and downloading. I'm working with Windows XP Professional (SP2).
After log-on to the sever I get a list of the files, but when I want to transfer I see only that the existing file is zero bytes. Also when downloading, the file is created locally, but keeps zero bytes.
What is happening?
Please Help me.
Regards and thanks for your help,
An up-to-now satisfied Dutch user