Hi Chrissie, sorry I didn't get back to you sooner. I wish I could add to Jenny's advice but I'm afraid I have nothing new to add. My only suggestion at this point would be to completely uninstall the game. I'm thinking your different ISP may be slightly different in its settings. Then reinstall the game and install the latest patch. See if that helps. Of course you will have to start over from the beginning.
Kay

Kay - I've tried reinstalling the game a few times. I have now also deregisterd first and thought I would try installing it again - but I have now had enough! - I may try again in the future! I am a bit disappointed but Acalius dropped through the letter box this morning
and I have several recent games as well as a backlog of older ones that I haven't got round to playing yet! (Hopefully none of them will be as much trouble!)
Thanks everyone for your help!