Loggin error: AppController not found

[Demonwolf37]

Fatal error: Class 'AppController' not found in /home/summonad/public_html/login.php on line 3

According to this thread (http://www.mysidiaadoptables.com/for...+appcontroller), this error is likely caused by,
1) A missing/blank .htaccess file
2) Incorrect config setup involving the domain name.

I don't believe either of these is the case.
1) There are 4 .htaccess files, one in public_html/inc/ckeditor/.htaccess(Which appears to just be legal information and tips instead of any actual code), one in public_html (which is a couple rewritecond, and rewriterule(s)), one in public_html/admincp/.htaccess (also rewrites, including rewriteengine), and one in install (which i've yet to delete, also rewrites).
2) define('DOMAIN', 'summonadopts.elementfx.com'); appears to be set correctly. The following does not produce any changes: define('DOMAIN', 'summonadopts');

Any other solutions that I appear to be missing?