Lion doesn't accept my passcode!! Please, HELP!

Hello everyone.

There is an issue with my Mac OS X Lion. Every time, when it asks my username and passcode there is an error. When I type in a wrong passcode the window is flickering and it says, that the passcode is wrong. That's fine. But when I type in my real working user passcode, the window closes and nothing changes. It doesn't proceed/accept my passcode; and it doesn't say, that the passcode is incorrect. The window simply closes and that's it.

Please help me! I'm sick n tired of this bulsheet.