macbook problems

Ok a couple days ago i was listening to my itunes on my macbook, all of a sudden it starts to skip (like a cd) so i turn the mac off. Well when i went to turn it back on, it went to the first gray screen for like 2 min, then it went black and "No bootable device -- insert boot disk and press any key" came up on the screen. So i pulled the HDD out thinking it was gone cause it started to make that ticking sound. well i went to the apple store, they said it was the hdd, so i ordered another one. put it in said the exact same thing. So im thinking its not the Hdd, i tried to other 2 i have as well (the original and one out of my buddies mac). So i dont have the slightest clue whats going on. Any help would be appreciated...

Rob

ok, i figured id try a hardware test. it said everything is fine.
ok new HDD - check
hardware test- done


could it be the logic board?
i sure hope it isnt.

ok so the last thing i know i do a PRAM reset thingy guess what.. IT WORKS.... The mac is ALIVE..

mods.. you can delete this..