Macbook won't load in normal, safemode or from installation DVD.

Hello,

I know there are a million threads similar to this one, but none I have read that answers my problem.

I have a Macbook 4,1 (early 2008), which stopped booting at the spinning gear. It would get into Safemode okay and I tried all the usual stuff (PRAM reset, SMC reset, etc, etc). I took it to an apple store who said I needed a new hard drive and to reinstall the OS.

So, I bought a new hard drive and a copy of Snow Leopard (had been using Leopard before). To begin with I kept getting to the spinning gear, but after a few attempts I got to the installation and it installed okay.

However, it still stuck at the spinning gear and Apple logo and could only be booted in safe mode. The next part of installation went nearly through to the end, but then it froze up and I had to shut down by holding the power key.

I got back into safemode and did a system update, but this froze when restarting the computer.

Now the laptop will not boot normally, in safemode of even to the installation DVD.

Can anyone help or suggest anything?

Thanks in advance.