Ok, I think I have the solution for this bug.
This is the situation: when you save WP Carousel standard options, it’s created a variable called $new_config in update_db.php. Later, update_db.php checks if that variable is set. If it is set, WP Carousel assumes that you have sent the standard options form, so it tries to update your Database with the content of that variable, but that variable does not have the correct kind of content, because it has not been processed the same way that it had been processed if you had sent the standard content form. In short, that variable should be unset when you send themes options form. That is the bug.
To fix it, simply open file update_db.php.
Go to line 172, you’ll see:
unset($config); // Eliminamos contenido innecesario
Replace it with:
unset($config); // Eliminamos contenido innecesario
unset($new_config);
Fixed!
I think this should fix the bug.
Thanks for reporting!