windows 8 installation has failed

Hey everyone! In a real bind here.

I have windows 7 HP 64 bit and dual booting Ubuntu 12.10 at the moment. I bought the windows 8 pro upgrade today (disc version) and I get through all the upgrading stages and everything seems fine then right before it finishes it has a error message

"windows 8 installation has failed"

Tried upgrading about 5 times now and its always the same thing. I have run the upgrade assisstant, and everything is fine. So frustrating :(

If anyone can help me I would be so grateful.

Peace.

Ben.