More info. Using Console I let it stream as I was in Usenapp. As it froze I see these messages:
database corruption at line 74317 of [02c344acea]
database disk image is malformed in "SELECT SUM(isread),COUNT(*) FROM msg_index;"
-[DBHeaders dbLoadMsgUnreadCount] database disk image is malformed
-[DBHeaders dbLoadMsgUnreadCount] Retry in 1 second. Attempt = 6
I do not pretend to fully understand that, but I am guessing that means the database is saved in a disk image and there is corruption there.