This is a strange one.

From have a quick play it appears that it's pages that would normally return a 404 that are returning the 500 error.

For example, your top level pages, like
http://2016.memedia.com.au/agency...
or
http://2016.memedia.com.au/blog...

Seem to work fine. So do your inner pages as you've described.

But a page that you don't have, regardless of the level seems to return the 500:
http://2016.memedia.com.au/spottedgoose...

So my guess is that you've overridden your not found page and something about that is throwing an error. I'm wondering if it's the server itself picking up the response code and then returning its own error page.

I don't think I've ever seen a 500 error like that before just spit out on the page as plain text.
Others might have suggestions as to where to look.

Amazing site by the way, looks spectacular!

Thanks for the quick reply Mesuva!

The 404 page does actually work, just not when it's at the root level. So for example:

http://2016.memedia.com.au/agency/spottedgoose...

Does work.

It almost seems like there's some sort of conflict with the homepage and the not found page. My suspicion is an error at the database level, as the same blocks and theme on a fresh install work fine. Finding that without a few clues could take forever.

Thanks for the feedback on the site design also, appreciated :)

Could it be some kind of looping redirect or error with your .htaccess file?

Unfortunately I don't think so - .htaccess is bare apart from the standard concrete pretty url code. Outside of that there is nothing else I can think of that would be causing a redirection on home.

Could it be some kind of looping redirect or error with your .htaccess file?