When your system remains idle for a specific period of time (10 minutes), the screensaver is activated automatically and to exit it, you have to submit your root password. If you find this behavior irritating, especially when you have a long password, then follow these instructions in order to disable the screensaver lock:
1. In the system tray, click the power button and select System Settings.
2. Under the Personal section, click Screen.
3. Click the lock button to switch it off.
4. And we are done, that's it!