I've been getting this message at the bottom of my screen with practically every click today - and often without a click. It's not happening on any other website.
'Internet explorer blocked this website from displaying content with security certificate errors'.
As the UK changes the default timezones for all PC's, i.e GMT > BST > GMT, then at sometime in the year the timestamp for the advert is out of sync with the current time, hence the issues as reported... It's up to the advertising hosting server to notice & sort out.