Steps to reproduce: click on button "Write" and Windows pops-up insantly the message "claws-mail.exe does not work anymore". Afterwards I can only close the program. The same happens when I want to reply to an email message. The Windows error message is not really helpful. It says that the program is not executed correctly and so it will be closed. Beside that Claws Mail works fine but of course it is a showstopper if I cannot write emails with it. The issue occured after I upgraded from version 3.11.1.
Does it also crash after you completely disable spell checking (Preferences, Compose->Spell Checking) ?
I opened the Preferences menu. When I clicked on Spell Checking under the Compose entry Claws Mail crashes again. So I cannot switch off the spell checking...
Do you by any chance have any files in C:\Program Files (x86)\GNU\Gpg4win\lib? Especially a sub-directory named "enchant"? If so, I suggest uninstalling Gpg4win and making sure the Gpg4win directory is completely gone. This is a somewhat known issue, and one that I have not found a proper solution for yet. What happens is that Claws Mail picks up spell checker libraries from older Gpg4win install path, instead of from its own, and they are not compatible.
In C:\Program Files (x86)\GNU I cannot find a directory Gpg4win. There are the sub-directories: - Claws Mail - GnuPG In C:\Program Files (x86)\GNU\GnuPG\lib there are two sub-directories (gtk-2.0 and kde4) and several files (charset.alias, libgcrypt.imp, libgpg-assuan.imp, ...). My Gpg4win version is 2.2.1. I just checked their homepage and saw that 2.2.5 is the current one. So I will update it as well and see whether Claws Mail works afterwards.
Ah, right, sorry, the package is called Gpg4win, but the install directory is named GnuPG. My mistake. Anyway, if you upgrade, and Claws Mail still crashes, try running it after uninstalling Gpg4win and making sure the GnuPG directory is completely gone from Program Files. (Don't worry, your settings are stored elsewhere.)
Ok, it works again. But I really had to to uninstall Gpg4win and to delete the GnuPG directory manually. Just updating Gpg4win did not work. Thanks for the hint.