I'm sorry you are having problems. Due to WordPress requirements, Flynn - the developer of Atahualpa, had to make some code changes.
One of these code changes can cause a conflict if 'Suhosin' is installed as part of PHP on a site. The solution is to tell Suhosin to whitelist the BFA code. This is detailed in one of the other posts.
Different sites have different versions of PHP installed. For example, on the host I use (I'm a long time customer) Suhosin is not part of PHP, however for new sites at the same host, Suhosin IS part of PHP!! (i discovered this when setting up a site fot a customer of mine) I guess that new users are on a different server.
Then comes the issue of how much control your host allows you. I can go in and edit the php.ini for my site and restate the server, others can add a php.ini override, some can't use a php.ini at all and have to contact their host's tech support to get past this issue.
Also, when you add a post to an existing thread it can get lost. My suggestion is one user/one issue pre thread.
If you decide to switch themes, I wish you best of luck.