The only way I could get round this in the end was to take a copy of the .ini file from my installation at work and change the obvious settings to work at home.
This on its own does not solve the problem as I have to cancel the dial-up that occurs when I start Gnutella and start up an internet connection separately after Gnutella has started up.
If I do not cancel the dial-up or if the internet connection is already open when Gnutella starts, I still get the Run Time Error.
I don't know if its significant, but every time I start Gnutella, it goes through the licence 'Accept' screen as if it hasn't fully installed. Could this be down to registry settings not being removed when I uninstalled it previously ?