Thank you George! once again, you had the right answer, alt+ctrl +delete gave me a dialog where I could change password, lock the computer or shut down. By fluke or design, this, I do not know, the shark was still running,I shut down and restarted and all is now well. Boy! have I learnt something to-day!... Time for a stiff drink now and my next lesson on Vista I had planned for this morning can now wait till to-morrow. Cheers now, Marie