Is Thunderbird still running? Check for a process thunderbird.exe in Windows task manager. If it exists kill it. Then try to start Thunderbird again.

I'm afraid it didn't help much, because it always resolves to that window, and, once closed, no thunderbird.exe process exists, and whenever I start Thunderbird it always proceeds like I described in original post.

Can you post a screenshot of your problem? http://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem

please see the crash window ---

Try to start Thunderbird in safe mode. https://support.mozilla.org/en-US/kb/safe-mode

Does the problem go away?

What extensions do you have installed? Please post your Troubleshooting Information. Help (Alt-H) - Troubleshooting Information

Right, it only works in Safe Mode... especially troubling is the lack of English language pack... I post troubleshooting info below ---

 Сведения о приложении

   Имя: Thunderbird
   Версия: 31.0
   User Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.0
   Папка профиля: Показать папку

             (Локальный диск)
   ID сборки приложения: 20140717165725
   Включённые плагины: about:plugins
   Конфигурация сборки: about:buildconfig
   Использование памяти: about:memory

 Учётные записи почты и новостей
   account1:
     INCOMING: account1, , (none) Local Folders, plain, passwordCleartext

   account2:
     INCOMING: account2, , (imap) mail.vfemail.net:993, SSL, passwordCleartext
     OUTGOING: mail.vfemail.net:465, SSL, passwordCleartext, true

   account3:
     INCOMING: account3, , (pop3) pop.inbox.ru:995, SSL, passwordCleartext
     OUTGOING: smtp.inbox.ru:465, SSL, passwordCleartext, true

   account4:
     INCOMING: account4, , (imap) imap.yandex.ru:993, SSL, passwordCleartext
     OUTGOING: smtp.yandex.ru:465, SSL, passwordCleartext, true

   account5:
     INCOMING: account5, , (pop3) pop.gmail.com:995, SSL, passwordCleartext
     OUTGOING: smtp.gmail.com:465, SSL, passwordCleartext, true

   account7:
     INCOMING: account7, , (imap) mail.*******:993, SSL, passwordCleartext
     OUTGOING: mail.*********:465, SSL, passwordCleartext, true

   account8:
     INCOMING: account8, , (imap) imap.gmx.com:993, SSL, passwordCleartext
     OUTGOING: mail.gmx.com:465, SSL, passwordCleartext, true

   account9:
     INCOMING: account9, , (imap) ssl.********:993, SSL, passwordCleartext
     OUTGOING: ssl.*********:465, SSL, passwordCleartext, true

   account10:
     INCOMING: account10, , (pop3) mail.**********:110, alwaysSTARTTLS, passwordCleartext
     OUTGOING: mail.**********:587, alwaysSTARTTLS, passwordCleartext, true

 Сообщения о падениях

 Расширения
   Allow HTML Temp, 3.6.4, false, {532269cf-a10e-4396-8613-b5d9a9a516d4}
   AttachmentExtractor, 1.3.5.1, false, {35834d20-efdb-4f78-ab77-9635fb4e56c4}
   Check and Send, 0.9.27, false, {1B0ADFEC-846C-401D-BA54-7842CBD485D4}
   Classic TB2 Options, 1.3.0, false, {2A95E724-F74E-46D3-93FD-3E9850382E53}
   Clippings, 4.1, false, {91aa5abe-9de4-4347-b7b5-322c38dd9271}
   CompactHeader, 2.0.8, false, {58D4392A-842E-11DE-B51A-C7B855D89593}
   ConfigDate, 0.7.5, false, {782E3D25-61FD-4997-AA8F-D3F18FA92ECC}
   Contacts Sidebar, 0.7.1, false, {4dce973c-25a5-4657-8e37-6c2a85c24a7e}
   ESET Smart Security Extension, 7.0.302.0, false, eplgTb@eset.com
   Get before Send, 0.8.11, false, {5FAC0DA0-1CB6-49D8-93FE-98714B81A8D9}
   MagicSLR, 3.9.1, false, {6e071e83-d8d6-8ca9-6129-eb8e8144596f}
   Noia Fox options, 3.0.0, false, NoiaFoxoption@davidvincent.tld
   Priority Switcher, 0.6.14, false, {0D2172E4-C5AE-465A-B80D-53A840275B5E}
   Quick Locale Switcher, 1.7.8.5, false, {25A1388B-6B18-46c3-BEBA-A81915D0DE8F}
   Quicktext, 0.9.9.9, false, {8845e3b3-e8fb-40e2-95e9-ec40294818c4}
   Silvermel and Charamel XT, 1.5.7, false, silvermelxt@pardal.de
   Simple Locale Switcher, 0.8.1, false, simplels@nohamelin
   Themes Menu, 1.19, false, {84625510-7e5d-11e0-a411-0800200c9a66}
   ThunderPlunger, 2.14, false, {bfec0750-aa6f-11db-abbd-0800200c9a66}

 Важные изменённые настройки

   Имя: Значение

     browser.cache.disk.capacity: 358400
     browser.cache.disk.smart_size.first_run: false
     browser.cache.disk.smart_size.use_old_max: false
     browser.cache.disk.smart_size_cached_value: 358400
     extensions.lastAppVersion: 31.0
     font.internaluseonly.changed: true
     font.name.monospace.el: Consolas
     font.name.monospace.tr: Consolas
     font.name.monospace.x-baltic: Consolas
     font.name.monospace.x-central-euro: Consolas
     font.name.monospace.x-cyrillic: Consolas
     font.name.monospace.x-unicode: Consolas
     font.name.monospace.x-western: Consolas
     font.name.sans-serif.el: Calibri
     font.name.sans-serif.tr: Calibri
     font.name.sans-serif.x-baltic: Calibri
     font.name.sans-serif.x-central-euro: Calibri
     font.name.sans-serif.x-cyrillic: Calibri
     font.name.sans-serif.x-unicode: Calibri
     font.name.sans-serif.x-western: Calibri
     font.name.serif.el: Cambria
     font.name.serif.tr: Cambria
     font.name.serif.x-baltic: Cambria
     font.name.serif.x-central-euro: Cambria
     font.name.serif.x-cyrillic: Cambria
     font.name.serif.x-unicode: Cambria
     font.name.serif.x-western: Cambria
     font.size.fixed.el: 14
     font.size.fixed.tr: 14
     font.size.fixed.x-baltic: 14
     font.size.fixed.x-central-euro: 14
     font.size.fixed.x-cyrillic: 14
     font.size.fixed.x-unicode: 14
     font.size.fixed.x-western: 14
     font.size.variable.el: 17
     font.size.variable.tr: 17
     font.size.variable.x-baltic: 17
     font.size.variable.x-central-euro: 17
     font.size.variable.x-cyrillic: 17
     font.size.variable.x-unicode: 17
     font.size.variable.x-western: 17
     general.useragent.locale: en-US
     gfx.blacklist.suggested-driver-version: 257.21
     gfx.direct3d.last_used_feature_level_idx: 1
     mail.openMessageBehavior.version: 1
     mail.winsearch.firstRunDone: true
     mailnews.database.global.datastore.id: c06b051f-9278-4aac-bb80-a5509ee06f8
     network.cookie.prefsMigrated: true
     places.database.lastMaintenance: 1406098387
     places.history.expiration.transient_current_max_pages: 104858
     places.history.expiration.transient_optimal_database_size: 30970675
     plugin.importedState: true
     plugin.state.flash: 0
     plugin.state.java: 0
     plugin.state.npadobeaamdetect: 0
     plugin.state.npctrl: 0
     plugin.state.npdeployjava: 0
     plugin.state.npgoogleupdate: 0
     plugin.state.npmeetingjoinpluginoc: 0
     plugin.state.npnv3dv: 0
     plugin.state.npnv3dvstreaming: 0
     plugin.state.nppdf: 0
     plugin.state.npspwrap: 0
     plugin.state.npvlc: 0
     security.disable_button.openCertManager: false

 Графика

     Описание видеокарты: NVIDIA GeForce 9600M GT
     Код производителя: 0x10de
     Код устройства: 0x0649
     Объём видеопамяти: 512
     Драйвера видеокарты: nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um
     Версия драйвера: 9.18.13.3788
     Дата разработки драйвера: 5-19-2014
     Direct2D включён: false
     DirectWrite включён: false (6.2.9200.16581)
     Параметры ClearType: Параметры ClearType не найдены
     Визуализатор WebGL: false
     Аппаратно ускоренные окна: 0

     AzureCanvasBackend: skia
     AzureSkiaAccelerated: 0
     AzureFallbackCanvasBackend: cairo
     AzureContentBackend: cairo

 JavaScript

 Инкрементальный GC: 1

 Поддержка доступности

   Активирована: 0
   Отключение поддержки доступности: 0

 Версии библиотек

     Ожидаемая минимальная версия
     Используемая версия

     NSPR
     4.10.6
     4.10.6

     NSS
     3.16.2 Basic ECC
     3.16.2 Basic ECC

     NSS Util
     3.16.2
     3.16.2

     NSS SSL
     3.16.2 Basic ECC
     3.16.2 Basic ECC

     NSS S/MIME
     3.16.2 Basic ECC
     3.16.2 Basic ECC

Then the problem is one of your add-ons. Are any of your add-ons incompatible with Thunderbird 31?

Well, it turns out none of my add-ons (fully compatible with 24.6) are compatible with 31. How that can be possible is beyond me... especially troubling is a lack of English language pack be it British or American, any...

Turns out I should have changed my posting from "I'm having a problem, could you please help?" into "T-bird 31 is having a problem, and should not be released". It turns out one is better off downgrading to trusted 26.4... Now, if there were an easy way to do that!

Absolutely worthless version, to even spend time discussing something that should have been done pre-release!

Well, it turns out none of my add-ons (fully compatible with 24.6) are compatible with 31.

I doubt that. E.g. you have 'Allow HTML Temp' version 3.6.4, and it is compatible with TB31. See https://addons.mozilla.org/en-US/thunderbird/addon/allow-html-temp

especially troubling is a lack of English language pack

Download and install the English version. https://www.mozilla.org/en-US/thunderbird/all.html

Absolutely worthless version

TB31 works fine here.

Update: all works fine now. For the record: Nothing was changed, amended or otherwise...just Mozilla coming back to its senses and fixing its own mistakes.

Issue closed.

p.s. how many more half-baked versions are we in for ?

I've had Thunderbird crashing lots of times during different upgrades (also on alpha and beta channels). For me it was solved by disabling FIPS mode before updating, running the update and then enabling FIPS mode again. Looks like FIPS and updates don't mix too well.

You can find FIPS under Tools -> Options -> Advanced -> Certificates -> Security Devices... On the right hand side is a button to enable or disable FIPS.

Thank you, Onno, a valuable pointer. I ll keep it in mind for any future updates.