Important Blank page on category thread Help!

Hello I have one category thread which gives a blank page.

www.fastingconnection.com/forum/40-Day-W...lled-water-fast.html

This is the link which you can access when you are logged out. But when logged in only a blank page.

I have not installed any new joomla comps or mods before it stopped working.

Latest joomla and kunena versions installed search engine friendly urls set to on and Use Apache mod_rewrite set to on (dont ask me why but if I turn it off nothing works)
Have turned off search engine urls but still problem persists.
Am using sh404

Any ideas?

Thanks

Hello,

You need to disable the component sh404 to see if the issue come from this, if this don't change anything you need to enable debug in joomla! configuration panel.

I will try thank you!
Dave

Hello and thanks for your advice. I tried a workaround where I created a new thread with similar topic header and proceeded to cut and post all posts in the broken thread which amount to about 15. My idea was once completed I would simply paste user name emial and id into the mysql database where relevant. I tried it on the first post and it worked. The issue I had however is that when I got to posting the 11th post I simply could not post a 12 post in the same thread. Every time I do it just gives me a blank page (only when logged in) So I had to delete post 12 from cpanel msql database table. Do you have any idea what is causing this anomally?
Thanks
David