Try closing TB and deleting the parent.lock file in the profile folder.

To open your TB profile:

- TB menu > Help > Troubleshooting Information

- click the Application Basics > Profile Folder 'Open Folder' button

If that doesn't work:

Close TB and open the Profile manager. Select the profile you want to use by default > check 'Use the selected profile...' > click 'Start Thunderbird'.

Also make sure TB menu > Settings > General > System Integration > 'Always check to see...' is enabled and click the 'Check Now' button.

Hi Ed, -Deleted the "parent.lock" file successfully but message remained on start, blocking my access to TB -Uninstalled TB and re-installed TB but message remained again blocking my access to TB -With message blocking TB opening page access I have no access to menu icon (=)/ help menu/ trouble-shooting -The problem and the message is now the same with Firefox ("Firefox is already running, but is not responding. The old Firefox process must be closed to open a new window")

More Help please Ed Malcolm

Did you try what I mentioned using the Profile Manager?

- press Windows Key+R on the keyboard. A Run dialog will open. In the Run dialog box, type: thunderbird -P. You can use -P, -p or -ProfileManager (any of them should work)

- select the profile you want to use by default > check 'Use the selected profile...' > click 'Start Thunderbird'.

Hi Ed, I have followed your instructions using the ProjectManager approach. It seemed to be progressing well until i pressed "Start Thunderbird" which triggered a pop-up box which stated "an unexpected error has prevented your changes from being saved". I repeated this several times but could get no further. Screen grab attached. Thanks, Malcolm

Hi Ed, I have followed your instructions using the ProjectManager approach. It seemed to be progressing well until i pressed "Start Thunderbird" which triggered a pop-up box which stated "an unexpected error has prevented your changes from being saved". I repeated this several times but could get no further. Screen grab attached. Thanks, Malcolm

OK, try the other profiles. If the same thing happens with them or of any start but don't look like they are current/working, delete all of them and create a new one.