Problems downloading Zipped Files

Previously was able to download zip files from an ftp site using Smartftp and was able to open them. Later on, my laptop was upgraded from Windows 2000 to Windows XP, supposedly Smart FTP was left off. I installed Smart FTP, followed guidlines required by FTP site from which we retreive files and after downloading a zip file, I received error when trying to open..."Cannot open file, it does not appear to be a valid archive If you downloaded this file, try downloading it again." I went and loaded the newest Smart FTP update and tried this again, but still have the same problem. Checked my Smart FTP with another user and settings under tools match exactly. Even tried uninstalling and re-installing, however Address, login, password and port was remembered after re-installing, so it's like something was stuck in my registry. Do you have any ideas how to fix my issue with opening the downloaded ZIP files? After trying to uninstall, is there any way to get things out of the registry....and what are they named?? This may be the root of the problem. Thanks, VCullop