Blogger has been having problems and outages lately; I think they were rolling out a redesign, or something equally major that turned into a disaster. A lot of us lost posts, temporarily, and couldn't access our blogs.
Blogger seems to have resolved most of the troubles — except that lots of us are now getting this "bad account" pop-up window. I know it doesn't exactly inspire confidence in me or this blog, but it's meaningless. It's perfectly safe to click it closed and read as you please.
I hope they fix this soon.... so far they haven't acknowledged the situation nor offered anyone an explanation. But I know I'm certainly not alone.
Update: Some brilliant blogger figured out that the "Bad Account" pop-up window is caused by a gadget called "FreeStats." Remove its HTML code from your Blogger template, and that nasty little window will go away.