I was having problems with the latest Filezilla getting blocked by the free edition of Zone Alarm. I followed GeorgeV's suggestions but they didn't help. However I have found a solution:

- Open Zone Alarm and go to Alerts & Logs > Log Viewer
- Try connecting to your server via Filezilla
- Then look in the latest log on Zone Alarm and look for the ftp connection getting blocked - for me it showed the ftp URL under Source DNS - but if not you may have to look via the source IP address.
- highlight the row with the correct log entry, right click and add to zone.
- this then adds the IP address of your server to the zone. if you ftp to multiple sites on different servers you will need to repeat for each one.

Hope that helps,