have you restarted your computer?

Hi Matt, I've tried all the obvious stuff.

• Restarting Thunderbird
• Restarting PC
• Reinstalling Lightning
• Reinstalling Thunderbird & Lightning
• Searching for fixes on the web

Many thanks for your help. Warmest regards, Andrew.

Well that has the basics out of the way... what remote calendars do you have? Caldav, gdata provider, ical Holiday calendars etc.

Hi Matt, None; all I'm using is:

• Thunderbird
• Lightning
• More Functions For Address Book

Many thanks for your help. Warmest regards, Andrew.

Hi Matt, I wondered if this might be relevant: https://ubuntuforums.org/showthread.php?t=2243503 Many thanks, Andrew.

LightningNever said

Hi Matt, I wondered if this might be relevant: https://ubuntuforums.org/showthread.php?t=2243503 Many thanks, Andrew.

I doubt it, I am guessing the poster there is using a ldap address book (active directory is one) lookups there are always slow and a minor change could make it very slow. But the split being discussed sounds like the server is not passing back an RFC complaint email address. Perhaps a delimited string of some kind.

Just a thought - sorry. It was the only post I found yesterday that seemed at all relevant. Many thanks.

LightningNever said

Just a thought - sorry. It was the only post I found yesterday that seemed at all relevant. Many thanks.

Nothing to be sorry about... you are at least trying. I can not knock that in any way. And I really do not know what the issue is, so it is not as if I am really all that much help.

You could try uninstalling lightning and reinstalling it, just in case there is an issue with the add-on registration. Sometime that fixes things.

I am a little short of time, but play with this search https://www.google.com.au/search?q=lightning+locks+up+site%3Abugzilla.mozilla.org leave the site filter in. If someone has reported a bug, even years ago, you might get closer to a solution.

Hi Matt, I've had a look but no joy, I'm afraid. Also with 'freezes' instead of 'locks up' - still no joy. I've already tried uninstalling & reinstalling Lightning. When that didn't help I tried uninstalling & reinstalling both Thunderbird & Lightning - still no joy. My Email & Calendar data was preserved (thank goodness) so not a completely vanilla install. I used Task Manager to make a dump file but it's 345MB... Many thanks for your help. Warmest regards, Andrew.

Are all your calendars functioning and synchronizing as they should? Odd things like this usually involve a problematical calendar or a read only one.

If you have a small calendar you could try logging https://wiki.mozilla.org/Calendar:QA_CalDAV_Support#Diagnosis_hints

Hi Matt, I think you're assuming that I've linked my Lightening Calendar with one or more external Calendars. This is not the case. I've kept things as simple as possible in an effort to avoid problems... Just:

• Thunderbird
• Lightening - no links to external Calendars
• More Functions For Address Book

Many thanks for your help. Warmest regards, Andrew.