My Macbook Pro displays a grey screen and a no entry sign. Help!

[Abughug]

Hi everyone, two nights ago whilst working on a word document and surfing the net, with facebook running, my mac pro, decided to fully freeze on me. it had the spinning rainbow wheel. Had to turn it off and restart.

On restarting, all I got was the initial grey apple screen, with spinning round grey wheel. Then after a bit of time the prohibitive (white, no entry) sign appears and it won't load.
I have tried everything in the Mac bible and also took it to an authorised Mac reseller, and they can't seem to sort it.
Sometimes it won't recognise the discs, when it does it won't allow any installation of the mac operating system on my laptop.
We did a hardware test and it comes back fine.
I have heard that it could be a corrupt file or something which is making my Mac think it doesn't have a valid operating system.
Please, any suggestions would help. :/

 

[miles01110]

Looks like a dead hard drive to me.

 

[Abughug]

Is that even though all the hard drive shows up when connected to another Mac? I could access all my files when he did this??

 

[JediMeister]

The prohibitory sign you describe could indicate improperly set permissions or a damaged OS. The unrecognized discs you can't install with, are these the ones that shipped with the computer or ones you pulled from a drawer? If not the discs that shipped with the Mac, are they from a later retail release of Mac OS X that you may have upgraded the system with?