So to solve this error you have to delete .android directory located in your user profile folder if you are using Windows and if you are using Mac, this will be hidden directory in your home directory.
So first of all make all the hidden directory visible. First of all open terminal and type following commands.
defaults write com.apple.Fider AppleShowallFiles YES
Now you have to kill all the finders and then go to home directory.
Now when you go to home directory you will see .android directory which was hidden.
Delete that directory and even delete it from trash.
Now restart the Eclipse and try to load AVD manager and Android SDK manager and it should work fine.