Do you see this with Firefox? What anti virus do you have?

My story with similar is here http://thunderbirdtweaks.blogspot.com.au/2016/08/windows-10-and-thunderbird-firefox.html

That largely fixed my issues. But not quite 100% I am still working on the last bit.

Reporter it would be helpful to hear your results. Please post them.

And if the problem has not resolved:

1. How long has this been happening and what changed in the time frame that it started?

2. Please start *Windows'* safe mode with networking enabled - win10 https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode Still In Windows safe mode, start thunderbird in safe mode - https://support.mozilla.org/kb/safe-mode-thunderbird Does problem go away? Please post your results.

I tried the fix that Matt suggested -- went to the YouTube video and learned how to change power saving setting to "high performance". Since then, so far, T-Bird has not frozen (yea!), but it's only been a couple of days.

I have not had this issue with FireFox, only T-Bird.

As for my antivirus, I'm using Bitdefender Total Security.

Alas, the power saving setting did not solve the problem. T-Bird froze again this morning for about 65 seconds. It usually happens as I'm scrolling through messages and deleting the ones I don't want. I will ht the delete key, then get the "Not Responding" msg for about 65 seconds. At the end of that interval, the email that I was deleting will be gone. Meanwhile, I can work with any other app with no problem -- the issue appears to be exclusive to T-Bird. Also, it's very random. Sometimes I will use T-Bird normally for a day or two - no freezing. Other times, it will freeze several times in one day. Going into safe mode and seeing if the problem will go away isn't workable because of the randomness of the issue. I need the full power and capability of my computer to run my business. In any case, I view the T-Bird freezing problem as a minor annoyance. It always resolves after 65 to 75 seconds, and while T-Bird is "not responding", I just work on other stuff.

Windows safe mode would help to determine whether anti-virus is causing the problem. It seems very likely though.

These are some generic suggestions wrt your anti-virus software.

Create an exception in your anti-virus software for the Thunderbird profile folder, so that the anti-virus real-time scanner will not scan it. http://kb.mozillazine.org/Profile_folder_-_Thunderbird

Don't let your anti-virus software scan incoming and outgoing messages.

Don't let your anti-virus software scan attachments.

Don't let your anti-virus software intercept your secure connection to the server.

Remove any add-ons your anti-virus software may have installed in Thunderbird.

Keep it working. http://kb.mozillazine.org/Keep_it_working_-_Thunderbird

If you have any difficulties making the suggested changes to your anti-virus software please contact their (Bitdefender) support.

I don't think I would like to prevent my antivirus from scanning incoming messages or attachments ...

> scanning incoming messages or attachments ...

is totally unnecessary, and a marketing gimick

scanning on opening of such things is sufficient to protect your computer.

Are you in the habit of printing your emails?

Restart Thunderbird. Does the hanging occur before you pint?

Latest attempts at fixing: contacted GeekSquad (I purchased the computer from Best Buy) and had them confirm that tbird is not connected to my antivirus, bitdefender, in any way. It was not and is not. Geeksquad then did a "tuneup" of the computer, turning off a lot of apps that were loading behind the scene on startup, updating a lot of drivers, etc. Since then (yesterday), the computer is very zippy, but the only app that continues to hang (temporarily) is tbird. As for printing, the hanging does not have anything to do with printing. I rarely print emails or attachments; tbird hangs regardless. However, the problem is very random -- it happens perhaps 1 in 5 times that I open my email to check for new messages -- and it resolves itself ("unhangs") after 65 to 75 seconds, so it's not that big a deal. Don't know what else I can do.

It isn't clear to me from your reply whether you did follow the suggestions given here: https://support.mozilla.org/en-US/questions/1139454#answer-919879

In any case, that's what you'd need to do.

If you have any problems following these suggestions please contact Bitdefender Support.

Yes, tried that. Did not work. But, as I've said, it's a minor problem, so I'm not much bothered by it.