Doing any write operation on the local keyring (I could reproduce with 'gpg --refresh-keys' and with 'gpg --receive-keys ...' as well) claws-mails kills the keyring when accessing it. So running one of the commands above and reading a signed mail at the same time you have to recover from backup.
tried to reproduce this. the worst I could do was to freeze Claws whilst --refresh-keys was taking place.
Hmm... I have never seen Claws blocking because of gpg activity. Possibly gpg and gpgme do use different lock files on my system? I will investigate further.
Uh, I had 'lock-never' in my ~/.gnupg/gpg.conf - so I should blame myself. This probably resisted from any tests I did... Sorry for the noise, please close the bug with invalid.
thanks for the follow-up