Thunderbird is set to open just like you closed it.

Do you use CCleaner software or anything like it? CCleaner thinks it knows best for you and basically removes the files Thunderbird has to remember those settings. Personally I would remove CCleaner from my system or at least tell it to leave your Thunderbird files alone.

Thanks for the reply but I do not have CCleaner installed on my PC. I do have Norton Security installed but I have not noticed that a Norton scan has identified any Thunderbird/Lightning files and removed them, it has only reported that browser cookies have been removed. Thanks but I regret that your suggestion does not apply to my PC.

If you need more information about my PC please let me know.

On the same PC I also use Thunderbird and occasionally use Internet Explorer. Explorer is used to access two web sites that do not play well with Thunderbird.

When this happens what is the status of Lightning when you look on the add-on tab?

I do not know the status of Lightning on the add-on tab when Lightning fails to open. The next time Lightning does not open when starting Thunderbird I will look at the add-on tab and report back the status of Lightning.

When I looked now, Lightning is displayed on the Extentions page under Folder Pane View Switcher and both Extentions appear to be active (the Options, Disable & Remove buttons are displayed).

On the Plugins page Shockwave 26.0.0.13.137 is shown as Always Activate. Would the Shockwave plugin slow down Thunderbird start up time?

Some add-ons have been known to cause problems. I have not used that one so I cannot comment on it. You could remove Lightning and do a fresh install to see if that helps. Your calendar data is separate from the program so it should not be affected. To remove click the Remove button beside Lightning. Then type lightning in the search box. Select Lightning when the search results come up and click Install.

I removed Lightning and did a fresh install. After the install all of my calendar events and tasks were there.

The next time Lightning does not start I will note its status on the Extention page in the Add-ons Manager and report it back here.

Thanks.

I hope you do not have to report back and the fresh install fixed it. ☺

Once again Lightning did not start/open this morning when I started Thunderbird. The only thing that I can report is that a Windows Java update appeared in the bottom right corner of my monitor almost intermediately after the Thunderbird panel was displayed (minus the Calendar & Tasks tabs). I shut down Thunderbird, started Firefox, installed/updated Java, started Thunderbird. Lightning started, displayed the Reminder panel with one overdue Task but the Calendar & Tasks tabs where not displayed with the Mail/Local Folders tab; they did open (Calendar & Tasks tabs) when selected from the Events and Tasks drop-down.

Hummmm.....anyone have any ideas other than reinstalling Lightning?

Thanks