There is a small thread about this in the support forum.
You can esc past this problem. Literally just hit esc on the splash screen and you can play, not logged in.
I had this problem also, used the shift tab, went to login in, and changed to my new password (I had changed my password since I bought the game). I had to do this even though I was logged into impluse just fine. I think this has something to do with the achievements they have added.
Another person posted that they had changed their e-mail and this caused that problem.
Possibly trying to loggin with your forum name instead of your e-mail might also help?