Cant unmount disk

[Redmelo]

Hello,

I've recently installed a new HDD in an MBA. I installed OS X and everything went smooth until I restarted. After the restart the notebook wont get past the Apple logo with that little turning wheel.

I am now trying to re-install OS X but am unable to because I get an error saying that the disk cant be unmounted.

I have tried pretty much everything I could find with google. Nothing works because the drive cant be unmounted. It cant be erased, partioned etc.

Obviously while booting from CD this should not be an issue.

What can I do now?

 

[flying grouse]

Can you get to disk utility: hold cmd+R when you power up. From disk utility, on the top bar there is an unmount tab, select the drive first, then unmount tab, and it will ask for your password.
you can also run disk verify and repair.