Setup was unable to download a required file

My Proclaim installation started displaying this message when it was trying to do the automatic update when starting Proclaim. I have tried uninstalling Proclaim and deleting the appdata/local/proclaim directory, but when  try running the proclaim setup program I get the same error. I also disabled my virus checker in case that was causing the problem.

Any clues to how to solve this - after unintalling Proclaim to try to solve the problem, I can't reininstall it now because of this issue!

Thanks

Jim