Skype Unable To Sign In

My Skype app stopped working today on my Android Galaxy S3 phone. When I tried to log in with the correct username and password, it said "Unable to sign in" every time. Skype asked me to reset my password, but I was not about to do that. I verified that I could sign in successfully on my computer and in a browser. So the issue was definitely on the mobile device.

This fixed the problem:
1. Went to Galaxy S3 Settings / Application Manager and selected Skype
2. On the Skype App Info screen, clicked "Force Stop" and then "Clear Data"
3. Received a pop-up message to the effect that this would delete every piece of data I have in the universe. Clicked Ok. Don't worry, it only deleted my Skype local app data on the phone itself (not my messages on the Skype cloud server).
4. Started the Skype app and it let me log in again!