it takes very little effort to try this to reinstall ffxp so...
it's very strange that when you are on a "limited" connection, ie behind firewall, the site works, but when on an open connection w/ dailup you would have problems..
can you paste status log when you try to connect in PORT mode?
another thing, i know you are running Kerio firewall, but did you scan your system for spyware? some of those nasties are replacing winsock files which can cause all sorts of problems..