Hi t-4-2 - thanks again, I thought that may be one of the only options left! Will try what you say first and if that doesn't work then will do a full uninstall and reinstall. Won't get round to that until the weekend. Just for your info the three main accounts that are duplicated all claim to be the default account - weird don't you think as you would presume that was not possible!
Thanks again for responding and will post the outcome of the efforts to put the thing right.