Unable to update page

I have been updating pages this morning just fine but now, after lunch, whenever I try to update the page I get the following error message (with both firefox and IE):

The connection was reset
The connection to the server was reset while the page was loading.

I was able to make the page I was working on private and that worked fine (I didn’t want clients seeing a half-written page) but I can’t update it. I even tried restoring a previous version and that didn’t work either. My site is here: http://www.silverphotography.co.uk

I’d be very grateful for any help.