Hello, I am trying to open the Thuderbird app on my Windows desktop PC, however I keep getting the following error message before the program even opens: '''``Thunderbird is already running, but is not responding. The old Thunderbird process must be closed to open a new window.``''' I have tried closing the background processes using alt, ctrl, delete. I also tried uninstalling, and then reinstalling the Thunderbird app from the setup file. I`ve also tried deleting the setup file, and installing it again fresh from the website. Every time, the same error message appears and I cannot open it. How can I solve this problem? Thank you so much.