Macbook - boot problems

Hi there, I'm having some trouble with my macbook not booting. It's 2.16GHZ white model from 2007 running leopard.

At first I was just getting a grey screen and nothing else, not even the startup sound. After resetting the PRAM i'm getting the flashing '?' folder when I just try to boot normally from the internal hard drive (320GB Hitachi).

When I boot from CD I can't see the hard drive in startup disk, but I can see the hard drive in disk utility, so I know it isn't completely dead. When I tried to repair the drive in disk utility I got the 'invalid B-Tree node size' error.

So, I completely erased the hard drive and successfully reinstalled OSX; or so I thought. It went through all the motions of a successful installation, at the end I was prompted to restart the machine as usual, and I did - except the machine wouldn't boot up and came up with the flashing '?' folder again.

I booted up in 'Apple Hardware Test' mode and did a complete test, no errors were found.

I am completely stumped, if anyone has any suggestions please post them.

Thanks
B

Your hard drive has gone south... (it's defective) and should be replaced. No amount of formatting and reinstalling is going to work. The invalid B-Tree node size error is fatal. As inexpensive as large hard drives are, just replace it.

Thanks for the reply. I'll install a new hard drive and see how it goes.

Cheers
B