Sensor only responds once in game logic

[bill2reg]

I've started working with simple game logic controls. When I use the LMB during game play, I have set it to restart the game. It works once only, and when the game restarts, it no longer responds. I have to hit the ESC key to quit the embedded game player. If I then start the player again, the LMB will restart the game once, but only once, then I have to use the ESC key again, etc. Blender 2.63. Is this a bug or is there something I'm not doing correctly?
Any help is always welcome. Thanks.