Messenger for Mac Will Not Sign In

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Whenever I try to sign in to Microsoft Messenger for Mac, it says my username or password is incorrect. I tried going to the Hotmail site to try to sign in there and see if my username and password was really incorrect, but it wouldn't even let me get to that site. It said "Address Not Found" every single time.

My internet is fine, I can get to any other site and sign in to any other messenger. I tried restarting Microsoft Messenger, and downloading the latest version of it. I also tried restarting the whole computer. Nothing worked.

The only thing I think could've caused this is that I just recently downloaded a security update for my Mac that it automatically picked up. But even if that's the problem, I don't know how to fix it.

Any help would be greatly appreciated.