Well I am very grateful for the prompt replies from ShareCG staff, even though they could not fix the problem - it not being at their end.

So in case anyone else has a similar problem, it turns out it was having the "banner blocker" enabled on my Kaspersky antivirus protection.  This stopped the page displaying - at all.

It also seemed to stop you from being able to use the "back" button on a webpage.

Weird!

But it's fixed now, so thanks to all.