Siteframe uses the mysqli interface - http://www.php.net/mysqli - you need to check with your hosting provider and make sure they're compiled PHP with the mysqli extension. The message is a bit confusing since, if it can't find a class, it looks in the includes/ directory, but mysqli is a compiled extension to PHP, not a source file.

Great, well I've sent an email to my host. Guess we'll see how that goes. Thanks for the fast reply.