For several days I had a problem logging into my Twitter account. I wondered at first whether I had been banned for some reason, but I couldn’t think of any reason for that. Then I checked that I could see my profile when not logged in, so all was well there.
Unfortunately, as soon as I logged in, I I went straight back to the fail whale.
To make a long story short, this behavior continued until I logged in using Tweetdeck. After that, I could log in with my browser again. I have no idea why this should be, and no way to duplicate the problem, but just in case it might work for someone else, I thought I’d document it.