WDTBD & Mark - Thanks for taking the time to reply - much appreciated. This does happen in 'safe mode' and followed the installation of a new version of I.E. from a new ISP, which I have since stopped using. I have looked in the start-up menu and am not sure which programme to uninstall and so am wary of causing some serious damage. It's just this box that pops up. It does not automatically seek an internet connection.
I would be grateful for any other thoughts, as it's really irritating. (I have tried a search on Microsoft.Com, with no luck) Thanks again.