I had the same general thing happen back in the 90s when I had a Mindspring account. I could see the account but couldn't do anything with it. I called tech help and the guy told me the problem was the account was over-full. I hadn't checked it in months and had been overly enthusiastic about handing out my e-mail address. The fix was the tech deleting e-mails to drain it down to a reasonable size. Better than 90% or it was spam so I didn't miss much.

Worked fine after that.