Try logging into your webspace from another pc if you can and then you will know if it is a local problem or a freeserve problem
I had the same problem as you with oneandone, getting the same error message but it ended up being a local problem, luckly i was about to do a re format/fresh install of windows anyway , and once completed i could access my ftp no problem ( i am not saying to re format) but try and remember if you have changed any settings on your pc that may be causing this
And when i use sygate, unless i create a advanced rule for my ftp address, i cannot access so you might need to change your zone alarm settings
Or i may be talking out of my arse and it could all be down to wannadoo/freeserve