2009 mbp 17 inch shuts off at boot

[Imacman65]

hi all

i have a 2009 macbook pro 17 inch (early 2009 2.66 ) and it shuts off at boot , not all the time but maybe 2 out of five times , i thought it was a keyboard problem so changed it and it had a speaker not working so i changed it also , i cleaned it all and put new thermal paste and it still does it , any thoughts on what to look for now ?


thanks

 

[Imacman65]

now it only starts 1 out of 5 times , and i have to press the power button twice to start after it shuts down