I had already cleared my cache and cookies but after you found this link (ver useful, thank you) I found somebody else with the problem and solution. They were told a different way of logging in and that seems to have worked for now. Fingers crossed!
Any ideas about imageshack. Do I need to get rid of the link that I have posted there?
Thanks for your reassurance Brundle. Yes I did try VoG's link and whilst it did not take me to the immeditate solution, it did take me to where I could find the answer. So I am very grateful. It seems to be signing out ok now. I keeping my fingers crossed.