Hi All, I'm hoping you can help as will be switching to Outlook office wide if can't get this issue fixed. We use yahoo bizmail/calendar here. Thunderbird works fine. Lightning doesn't. Lightning used to work great and sync to our yahoo caldav calendar great but with recent upgrades we are having nothing but problems. First it started putting all our meeting invites 7 hours off. Everything was in UTC so we had to create duplicate events. This is office wide. and yes all calendars yahoo and lightning are set to Pacific Time. This was only in my synchronized yahoo calendar, not in my default thunderbird calendar. Now it is getting much worse. Currently we can't accept meeting invites and get processing error for both synchronized yahoo calendar and default thunderbird calculator. First time you click accept nothing happens, second time "Processing Message Failed. Status: 80004005" IT will also no longer send notifications. Finally it won't allow me to invite anyone to a meeting. So I have tried a complete uninstall and fresh new install, not linked to any old profile, nothing changes. I'm currently running Thunderbird Beta 30.0 and Lightning 3.2b because the current 24.5, etc didn't work. All with the same issues. Any help? Thanks