Start *Windows'* safe mode with networking enabled http://windows.microsoft.com/en-us/windows-10/change-startup-settings-in-windows-10#v1h=tab01

Still In Windows safe mode, start thunderbird in safe mode - http://support.mozillamessaging.com/en-US/kb/safe-mode

Does problem go away?

I tried that before I posted my question. As. I said it's not a driver issue (bad Windows driver or third party driver). Nor is it an isolated case. There are similar posts in Microsoft forums, Windows forums (non-Microsoft), and sites like Symantec\Norton. All have the same issue; Thunderbird 38.1.0 freezes running under Windows 10. It has got so bad and so frequent, that I have stopped using Thunderbird.

Yes, but running Thunderbird in its own safe mode eliminates problems caused by its own add-ons and its hardware acceleration. Don't assume that all the help is simply trying to point the finger elsewhere.

I don't run any Thunderbird add-ons, besides, as I just indicated, running it and Windows in Safe Mode did not resolve the issue.

The "usual" advice is pro forma the best first advice that helps most users. And the sake of education, addons is only half of what safe mode covers.

There are a few crash reports, even hangs and most of those have been driver releated. But there are currently no Windows 10 performance issues reported in our bug databse http://mzl.la/1TrnHKy and there are plenty of windows 10 users using Win10 without problems. So that's where we sit.

I hope Zenos can take over because my next project is readying the next release. But I think next is to ask what you to provide more detail - for example what antivirus do you use, when does it hang, etc

p.s. https://support.mozilla.org/en-US/questions/1077179 is an example of safe mode usefulness

I use Kaspersky antivirus, the same anti virus which has been working flawlessly with Thunderbird, and vice versa since I built (not to be confused with assembled) my original system from the ground up back in 2010. I have continuously updated the hardware each year, since then. My current motherboard is custom-built using the X99 chipset with an i7-5960X processor and two EVGA GTX 980Ti GPUs.

I just read a blurb where putting an exception for THunderbird in Kaspersky solved a user's problem. Does it help you as well?

Again, Thunderbird has been working flawlessly with Kaspersky for years. The problem only appeared after upgrading to Windows 10.

gsmith55 said

Again, Thunderbird has been working flawlessly with Kaspersky for years. The problem only appeared after upgrading to Windows 10.

That's great. And we understand that. But it doesn't change the advice that's being offered.

When I have already said two or three times that there have been no issues with any program over the years until Windows 10, what value is there in telling me to add Thunderbird to the Kaspersky exception list?

Tell you what, thanks for the feeble attempt at helping with the problem, but the "advice" has been worthless, and ignores everything I have already said about the problem. No further "advice" is needed, I will look elsewhere for real, knowledgeable help,