I just attempted to edit a post after chef pointed out an error I'd made in it. The thread contained only two posts, mine and chef's. I chose edit in the original post, made an edit and chose "submit". At this point I got the following error:
SQL ERROR [ mysqli ]
BIGINT UNSIGNED value is out of range in '(`phpbb3`.`phpbb_users`.`user_posts` - 1)' 
An SQL error occurred while fetching this page. Please contact the Board Administrator if this problem persists.
I went back in the browser, attempted to "preview" and this time I got told the post no longer exists. Sure enough, when I look in the board I posted in the whole thread's gone! It was called, "Samsung SH-223L".
I'll repost, but I just thought you should know.