My pc is shutting down after some time, What can be problem?

[jayant]

Hello friends,

 When i start my pc, it's shutdown after sometime automatically and if i start again then it sometime shows "Boot from cd..." option.

 Also, my mouse wont work sometimes, it will pause there and i am not able to click or move cursor. Also, sometimes all event start automatically like opening my computer and closing firefox etc...

And main problem is when i take him to expert, it will work for him as it works sometimes and he can not find problem so please help me on this.

Please help me on this problem.