Macbook Will Not Start Up

[plzhalp]

I bought my mac book about a year and a half ago. Its worked amazingly up until about a few months ago. It started out by just freezing every now and again. Then one day it decided to just shut down randomly. I tried to reboot but it would get to the grey screen with the apple and stay there with a "do not enter" symbol which im assuming means it cannot boot... Ive used the disk utility and when it was freezing i checked its permissions multiple times. So i reset its pram and did an erase and install. worked fine for about 2 weeks then did the same thing. Accept now reseting the pram does nothing and the disk utility comes up with nothing... its a macbook 4,1 2.40ghz

I dont really know much about computers if you can tell PLEASE HALP!

 

[Giaguara]

It could be somehting with the hardware so let's see if a hardware test will give more clues on what's happening there
http://macosx.com/forums/howto-faqs...are-test-other-diagnostics-test-hardware.html

 

[djackmac]

So i reset its pram and did an erase and install. worked fine for about 2 weeks then did the same thing. Accept now reseting the pram does nothing and the disk utility comes up with nothing... its a macbook 4,1 2.40ghz

Elaborate on disk utility does nothing. Does disk utility see the drive? Do you run repair disk and if so what does it come up with? The more information the better if you want an answer.