Help: Cannot boot into Disk Utilites. Is there a workaround?

[NJRonbo]

Boot and hold down the C key.

Always worked for me.

Now, it longer does on my iMac.

The computer boots to the white screen with the apple logo and just hangs.

I tried it with both Snow Leopard DVD in the drive and without. Both same results --- it just hangs.

Any reason why it isn't working? If the Snow Leopard DVD is dirty and can't be read could that be a reason?

Thanks