I have no clue what's been going on, as I haven't changed any commenting settings in several months. However, blogger did just update to a new version and I'm assuming that's where the snafus have occured.
I'll have a look through the FAQ's and help pages to see if there's anything on it. If I can't find anything, I'll see if I can't Email someone about it.
But if all else fails, feel free to Email me and let me know what you're thinking!
Update: One thing I've found:
Users who have their Internet Explorer security settings set to “High” may have trouble logging in. After sigining in, they see a “Click here to continue” link that does nothing. One workaround is to right-click on this link and choose “Open in a new window.”