User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/43.0.2357.130 Safari/537.36 Steps to reproduce: Thunderbird updated to version 38, Lightning updated to 4.0. computer crashed (freezed and had to be unplugged) at least 10 times while it was running. Did not crash when it was not running. time until crash varies from some minutes directly after reboot to some seconds after longer run of computer. other applications not needed for crash. installing thunderbird 37, lightning 3.9 solves problem, no crashes any more. Actual results: computer crashed (freezed and had to be unplugged) at least 10 times while it was running. Did not crash when it was not running. time until crash varies from some minutes directly after reboot to some seconds after longer run of computer. other applications not needed for crash. new incoming emails almost certainly lead to instant crash. Expected results: computer should not crash with this reproducablity with current thunderbird version.

This may be a hardware-acceleration issue. Click the [≡] button on the main toolbar and select "Options" then go into the "Advanced" category, "General" tab. Uncheck "Use hardware acceleration when available" at the very bottom of that tab and see if it resolves the problem.

(In reply to rsx11m from comment #1) > This may be a hardware-acceleration issue. Click the [≡] button on the main > toolbar and select "Options" then go into the "Advanced" category, "General" > tab. Uncheck "Use hardware acceleration when available" at the very bottom > of that tab and see if it resolves the problem. If that helps, please also tell us the graphics card, and driver version and date. Thanks ( http://forums.mozillazine.org/viewtopic.php?p=14216093#p14216093 also reports strangeness starting in version 38, but not a hang)

It seems to help. My graphics card is: NVIDIA Quadro NVS 285 10/28/2013 Thanks a lot.

Paul, if you reenable HWA do you still see this problem?

(In reply to Wayne Mery (:wsmwk, use Needinfo for questions) from comment #4) > Paul, if you reenable HWA do you still see this problem? Thunderbird version is 42 and HWA enabled since yesterday. No hang yet. I would say I do not see this problem now.

(In reply to Paul Stoll from comment #5) > (In reply to Wayne Mery (:wsmwk, use Needinfo for questions) from comment #4) > > Paul, if you reenable HWA do you still see this problem? > > Thunderbird version is 42 and HWA enabled since yesterday. No hang yet. I > would say I do not see this problem now. with the same date of video driver? 10/28/2013

(In reply to Wayne Mery (:wsmwk, use Needinfo for questions) from comment #6) > (In reply to Paul Stoll from comment #5) > > (In reply to Wayne Mery (:wsmwk, use Needinfo for questions) from comment #4) > > > Paul, if you reenable HWA do you still see this problem? > > > > Thunderbird version is 42 and HWA enabled since yesterday. No hang yet. I > > would say I do not see this problem now. > > with the same date of video driver? 10/28/2013 Sorry. The driver date is 1/30/2015.

Paul, Do you still have problems in version 45 with HWA enabled? If you do still see problems, is it better with (in this order) 1. current beta from http://www.mozilla.org/en-US/thunderbird/channel/ ? 2. latest NVIDIA driver ?

Ah, I missed comment 5. Assuming HWA is working for you unless you post otherwise