Thanks for your reply. No I do not use NIS but use AVG which I have not known to obstruct any previous programme including AdAware SE.
I am new to this forum and thought that I had posted my reply before but I may have done something wrong. Hope this brings more information. Since my original enquiry I have run programme repair in Add/Remove programme, but the results are just the same. I think I am just about reaching the point of giving up Regards Carper