Frontpage editor not working

Unfortunately sh4040sef is a commercial product, thus I can't test it myself.
What happens if your directly access the view without the &tmpl=component and without the modal window? Just copy the link into the browser address window and delete the &tmpl=component.

Especially the scripture window isn't anything special. It's a regular view without any special parameters. So if this doesn't work it's most likely a bug in sh404sef.

Thomas, these problems also occur when I use the Joomla SEF and disable SH404SEF

When I try to access /scripture it works. I get the scripture selection embedded in my website.
But when I try to access /scripture?tmpl=component I get the Not Found message.

Then it sounds not like a SEF issue but a template issue.
Can you check in the folder of your template if there is a file named component.php (/templates/your_template/component.php).
If this is missing, then you need to add it. It's a "must have" file for Joomla templates and is used for outputs without any modules loaded (like out modal window).

If that file is there, maybe you have to check the server error log to see what exactly is not found.

Hi Thomas, the file was there. My problem was caused by a too strict rule in my .htaccess file. Problem solved.

Ouch... Wouldn't have searched there as it usually gives a "not allowed" type answer, not a "not found".

Glad you found the culprit.