I recently installed KishKish, a program that allows one to record conversations on Skype. I noticed that the add-on causes, you to log out of Skype and when prompted to log back in, there's a bug making it impossible to log in because the password fails.
No matter, how many times you double-check your password or re-enter it, you won't be able to log in.
Solution
Close the Skype program completely then reopen it. The password should work properly this time and you should be able to log into Skype like normal.
Update: Amolto is a Skype plugin and I've found it to be better than Kish Kish.