>Over the weekend, I noticed that when I logged in, I'd get all messages going back two days.

Could it be the click was on "Try it before creating an account"? This is basically what it does.

>When I tried to post a new message or reply, the bottom pane would stay grey and no text box nor message buttons would appear.
>Today can't even log in with Edge. The toolbar tells me I'm logged in as "anonymous"
>
>Using IE 11:
>To post this message, I logged in with IE 11. I still to all messages going back two days.

Based on that, it appears you are logged on as anynomous.