No password entry box but still able to type in password as normal, and no background displays, only a weird purple dotted background.
Marking this as "invalid" for greeter. It looks like you've installed unity-greeter. This is probably a side effect of installing unity tweak tool. Uninstall unity-greeter and reinstall pantheon-greeter.
Bug watches keep track of this bug in other bug trackers.
Marking this as "invalid" for greeter. It looks like you've installed unity-greeter. This is probably a side effect of installing unity tweak tool. Uninstall unity-greeter and reinstall pantheon-greeter.