Everyone is a tester on file sharing apps like Limewire. There have been many many versions over the years, and to my knowledge there has never been a single version out that didn't cause some people trouble Mostly because of user error or inexperience

On all the computers around the world that have Limewire installed on them, there are literally millions of different setups, versions, programs already installed, etc, etc. It is simple unavoidable that someone will not run into trouble on some version. Bare in mind that there are millions of people that use current versions of Limewire and have no problem at all doing so.

Now you say that you know the guy running your ISP and he says his isn't working either at the same time. Shouldn't that be telling you something. It sure is telling me something, I can tell you. I tells me that while before I was 99% sure that it has something to do with your internet connection, I am now 100% sure.

You even tried downgrading and that didn't work either. So what I would suggest is that you have another talk to your ISP guy and ask him to figure out what has changed.

For an example. Is there maybe just a slight possibility that your ISP is a branch of a bigger ISP that has in fact started blocking Limewire.

And Last but not least (to the best of my knowledge). No there is currently no version that has the kind of packed encryption that would be needed to get past an ISP blocking Limewire. Some have had success using Proxy and tunneling (which I must admit, I know absolutely nothing about) to get it to work.