Andaravi, Tarun, Thanks. I checked your statements and you were right. Firefox did not appear as an appication but as a process. As long as the process is not "killed", the message from CCleaner appears. As soon as firefox process is "killed", CCleaner runs smoothly. I documented these steps and attached as jpeg files. CQFD Thanks again.
In revision 1.31.325, even after closing ALL Mozilla Firefox browsers ( Firefox V 1.50.4), when running CCleaner, a pop-up message shows up indicating: " You must close Firefox/Mozilla to allow the Internet cache to be cleaned. Otherwise, this process will be skipped". This did not happen before I updated to the latest CCLeaner rev. Keep the good job. Thanks.