"An established connection was aborted by the software in your host machine." <- occurring randomly

I get the above message when I try to access my FTP site. It happens 1 out of 3 times and seems to happen randomly. I've tested it on smartFTP (on my PC, wired to a router), and DreamWeaver as well as my Mac computer connected wirelessly. I've contacted my host and they're telling me it's software in my machine. Still, how could it be that it's happening on two machines, with different brands of software?

a sample of the smart FTP code that generates when this problem occurs:

[18:13:34] CWD /public_html/joomla/templates/siteground/css
[18:13:34] 250 OK. Current directory is /public_html/joomla/templates/siteground/css
[18:13:34] PWD
[18:13:34] 257 "/public_html/joomla/templates/siteground/css" is your current location
[18:13:34] PASV
[18:13:35] An established connection was aborted by the software in your host machine.
[18:13:35] Server closed connection

In order for me to actually see the contents of the above folder (though it could be any folder on my site), I then need to press the "refresh" button numerous times until finally it decides to reveal the contents of the folder. Then, mysteriously, the software acts as if nothing's wrong. Until it decides to give me the above message again.

What do you guys suggest? Is it a problem with my software? Windows? Or could be my Linksys router?

thanks for whatever input you might have


It's a network/NAT/software firewall router problem. For a detailed analysis please purchase a license at: