broken post via comment/s? help!! please!

hello – going mad here as I can’t seem to solve this….

I wrote a little tutorial a while back for the firefox extension FireFTP – everything was well – the post was quite popular, getting a few comments from people.
My blog including all pages, posts, single post pages etc worked 100% fine – so I assume I do not have problem with my templates.

At one point – all of a sudden it seems there is something seriously wrong… when the post shows up on the blog via the category – the layout breaks (footer shifts): https://www.graphiceyedea.info/wordpress/?cat=9 [4th post down]
on all other pages – the layout is always fine….

Once I click the post title, ‘read more’ or the ‘comment’ link – the page appears correctly in the addressbar – but remains stuck in a loop somehow…..!??!

if you do a search for the post – the layout does not break – but still I cannot get to the post’s own page….!?
https://www.graphiceyedea.info/wordpress/?s=fireftp

how odd….. I’m really REALLY stuck here – hoping for some enlightenment from some of you experts out there…?!

how do I solve this…?
I’ve been through the comments – unapproved a few which contained elements on code, just in case …. double checked my templates (which were working fine for ages – and don’t have this problem on any other posts) – can’t think of how to find what’s causing this error…..

help please!!!!!!!!!!!!!!!!!!!!