remove the calendar entirely.

How do I remove the calendar? "Events and Tasks -> Delete Selected Calendar" will not start/open.

You said you uninstalled it. How did you manage to do that? Lightning is an add on. You go to the add on tab in Thunderbird, click extensions. Is Lightning listed? Is it Disabled? You have the choices to enable or remove the Lightning add on here.

Thanks for your response. I thought you meant Calendar-Delete. Yes -I previously disabled and removed Lightning (Tools -> Add-Ons), then re-installed Lightning - still had the problem. I assume the problem is somewhere in the saved settings and data. I started Thunderbird in Safe Mode - Thunderbird worked fine, but no calendar (all add-ons/extensions disabled, including Lightning). I also disabled all the add-ons except Lightning, and still had the same problem. Before I started removing things from .default folder (like Calendar directory), I thought I'd ask if that was wise.

In order for us to better investigate this issue you need to add a little more non-personal information.

Please add the troubleshooting information to your post To find the Troubleshooting information:

• Open Help (or click on three-line-icon and select Help)
• Choose Troubleshooting Information
• Use the button Copy to clipboard to select all. Do not check box "Include account names"!
• Paste this in your post.

Please also add the result of these troubleshooting steps to your post

• Does Thunderbird work in TB Safe mode (see Thunderbird Safe Mode)?
• Do you use anti-virus and firewall software? What is the version?
• Who is the email provider?
• Who is the internet provider?
• What is the exact error message?
• What steps did you take right before this happened?

Please post back with this information and any other questions you might have.