Blogger had a problem last night, unrelated to the disqus problem, which threw up a scary red security screen for people. Supposedly fixed.
Had more reports that fixing/switching the DNS has solved the problem for people. Use your ISP's default, or if that is the problem, try switching it to one of the public ones (google, opendns, cloudflare). Here's some help for windows.
I managed to get a response from disqus which was a nonresponse (EVERYTHING IS FINE). Anyway pretty sure what happened is they made some switch at their end which didn't get propagated to all the DNS servers correctly. All this is a bit above my pay grade.