Toshiba Satellite Turns on for 5 secs.

My Satellite m45 s 269 turns on for about five seconds then shuts right off. At times I press the start button and maybe 5 seconds after I press it, it will turn on for only about 5 seconds and shut right off. My father inlaw seems to think I need a new internal power supply. My first indication something was wrong was when it started freezing up on me in the middle of anything i was doing. This started happening at random times. Please help. Thanks in advance.