The new build that i put together for my son has a 500GB Sata hard drive. I also installed his old 80GB IDE hard drive as the board has an IDE port. The problem is that before and after formating it's only seen as 40GB.
Typing 'DISKMGMT.MSC' brings up the 'windows cannot find' error for some reason. I will have a look at the manufacturers website later when i get home. I realise that i haven't installed the motherboard driver disc yet. Could that be the problem?
If you go via control panel through admin tools you should be able to get to disc management that way and as long as there is no corrupt sectors you should be able to restore and format entire disc that way.
If not go with other suggestion of makers diagnostic software which should be free to download from their web site.