I can sign in using my windows live ID on your website and see my past uploads, but these days after I upgraded to ios5.1, I find that i can't sign in with my windows live ID in your app anymore. It says my username or password is incorrect. I'm confused about that. I'm using the right account, both he username and password, and I can sign in on your website.

Zconomy, does your password have more than 16 characters? 

If so, try entering only the first 16 characters of your password or resetting your password at http://account.live.com/ where they no longer allow the registration of passwords longer than 16 characters. 

If either of these work for you, please write back and let the rest of us know.

I Can't sign into Windows live from the app.
When I try it gives me a screen to create a username which I already have.
And won't give me any further options to enter my Windows live ID