Php error log would be the first thing.
Failing that - what is different (in form, functionality etc) between that particular page and ones that do work OK.

Hi
thanks for the reply. I can't see anything in the error log about this page. It still loads the header and the nav:http://www.ingleandrhode.co.uk/index.php?cID=442...
It shares its pagetype with other pages but I'm not sure what other content is on it to be honest. How do I go about debugging this issue?
Thanks

Ok so I have an editable area called "banner". If I remove that, the rest of the page loads. Would could be the issue with this area?

A generic list of things to check
http://www.concrete5.org/documentation/how-tos/editors/the-block-do...

You are probably beyond that by now, so I posted the above for the benefit of others coming to this thread.

Thanks John I'll work through that list. If all else fails, is there a way of manually removing blocks from an area in the DB?

Hi,
I don't think it's anything in your list, what about manually deleting the block in the DB?

Manually deleting a block from a page is not straight forward. There are several tables involved and they all need to be consistent.

Can you not just uninstall the block? Or go to the sitemap in the dashboard and revert the page version?

If that doesn't work, I would try creating dummy view and/or controller overrides for the block that do nothing. That should enable the page to render or edit with the dummy override in place of the problem code so you can delete it.

I'd rather not uninstall it because it's on countless other pages and working fine.

Basically one or two pages have this issue after migrating the site from another server, but I will check page versions next.