Android Struggle - Re-installation failed due to different application signatures

What do you do, when you encounter this?

Re-installation failed due to different application signatures.

You must perform a full uninstall of the application. WARNING: This will remove the application data!
Please execute 'adb uninstall [package name]' in a shell.
Launch canceled!

1) Open command prompt.
2) Go to [directory path]:\android-sdk-windows\tools
3) adb uninstall [package name]

Or you can always delete the app from the "Manage Applications" in your phone. Then install again.