FileZilla problem with MLSD command. Help Required

I have been having an issue with FileZilla for the last two days.

When I try to connect FTP via FileZilla, my connection is blocked after a few tries. My website seems to go completely offline for me.

But today someone added a comment on my site while my own bloody site was invisible to me. Forget FTP, even the home page wouldn't open in a browser. I tried with 2 different ISPs and the same problem occurs in both.

So, obviously I am doing something via FileZilla to get my IP blocked for a few minutes from the server. The site seems to come back online in a short while but I am unable to get a directory listing in FTP or upload any images (even via the upload image link in wordpress).

I use a Mac with the latest version of FileZilla and Wordpress 3.2.1 is installed. I have not upgraded to 3.3.1 since I am unable to take a backup either.

Edit: I am also unable to upload photos through wordpress.

Any ideas?