https://wiki.mozilla.org/Thunderbird:Testing:Antivirus_Related_Performance_Issues#McAfee

I did everything suggested that I could do. Could not disable MacAfee Anti-Spam from the tools menu because the add-on directory will not open. I've uninstalled and reinstalled 38.6.0 several times with MacAfee scanning and the firewall off, restarted the computer, everything I can think of. Still the same result. All folders show, mail is received, but no folder or tab can be opened.

From your last post it doesn't sound like your problem is solved. Why have you marked your post as 'Solution' then?

Try to uninstall Lightning and then re-install it from AMO if you need it. https://addons.mozilla.org/en-US/thunderbird/addon/lightning/

Also see http://xenos-email-notes.simplesite.com/416814616

I didn't see where is say it wasn't solved.

Situation has changed again! I have managed to get rid of the MacAfee Spam thing but...now I can open folders but only if I right click and open in a new tab. My address book and everything else on that bar is inoperable. Mail comes in, I can read it (once I've done the right click thing), delete it, file it, etc. Usually if I close TBird it won't reopen unless I reboot the computer. It is acting as though the app is still open even though it has disappeared from view.

I replaced my Profile with the one I'd saved at the beginning of this mess. That wasn't any help. BTW WRT Lightning: I haven't seen the Calendar tab or any of the associated icons on the upper right since this problem started (and of course) I can't open the Add-on file.

Latest: I've completely uninstalled McAfee Total Protection, "uninstalled" TBird, reinstalled and nothing has changed. I can open TBird, see files and open them as long as I do so in a new tab. Can receive and read but not send mail, cannot see my address book or any of the calendar bits. Can view account settings. Obviously I need a more complete uninstall but I must preserve my local files, address book and calendar files. What to do now? Again "closing" TBird doesn't really close it. The computer must be rebooted to truly close it.

BTW: the McAfee Spam folder has reappeared!

I've completely uninstalled McAfee Total Protection

Good.

"uninstalled" TBird, reinstalled and nothing has changed.

Not sure what you were expecting from re-installing the application. It usually is a complete waste of time, when the problem is in the profile.

Can receive and read but not send mail

https://support.mozilla.org/en-US/kb/cannot-send-messages

cannot see my address book or any of the calendar bits.

It is impossible to follow what exactly you were doing, so I'm not going to speculate about what happened to your address book. Wrt the calendar see https://support.mozilla.org/en-US/questions/1111007#answer-847401

Obviously I need a more complete uninstall

I have no idea what you're talking about.

"closing" TBird doesn't really close it.

What does this mean?

the McAfee Spam folder has reappeared!

What are you talking about?

Your thread is still marked as 'Solved' while it obviously isn't. That will likely prevent other contributors to look at it, so you decrease your chances to resolve your problem.

> ...now I can open folders but only if I right click and open in a new tab.

This sounds like the problem caused by Lightning addon after a Thunderbird update. Do you see the Lightning in Tools | Add-ons | extensions?

I have no access to tools, doesn't show up. I have no Calendar tab or any of the associated icons on the right end of the bar. I also I see no Lightning listings any where in my files.

I can't send messages or see my address book. I can receive mail and read it as long as I "Open in a new tab" every time. I can file messages and read old messages from my files as long as I "Open in a new tab" every time.

Would it be good to uninstall the program, manually remove all the TBird files in App Data, start fresh and then splice back in the necessary info from a Profile file that I have saved remotely?

Sorry for lack of response. Hopefully you have solved this by now, by starting Thunderbird in safe mode and disabling the Lightning/addon.

Are you good now?