Sorry, I should have mentioned this before - I've been getting the error every time I tried to access this site from at least a couple of weeks ago, though I haven't tried every day so it could be sporadic with me unlucky.

I don't have a problem with any other US hosted sites, in fact this is the only site I have the problem with.

My totally not techy guess was that perhaps someone with my server had been given a ban wide enough to block it all . . .