While trying to load my old Thunderbird profile data I must have entered an incorrect profile address, causing it not to load. I tried to correct this by deleting the new installation and reinstalling a new download, but now get the message: "Thunderbird is already running, but is not responding. To open a new window, you must first close the existing Thunderbird process, or restart your system." Task Manager shows no other instance running, so I have restarted the computer - same message. I have also closed the computer, waited and then restarted. Same message displayed. Please - Any suggestions as to how to overcome this problem?