Boot Camp error: The startup disk cannot be partitioned or restored to a single partition. The startup disk must be formatted as a single Mac OS Extended (Jounraled) volume or already partitioned by Boot Camp Assistant for installing Windows.

Hi!

I am getting the error:

"The startup disk cannot be partitioned or restored to a single partition. The startup disk must be formatted as a single Mac OS Extended (Jounraled) volume or already partitioned by Boot Camp Assistant for installing Windows."

I read up some on google, but all of them says that they have crated a partition and that is the problem, I only have the standard "Macintosh HD".

I tried to create a partition manually in disk utility but then the error message: "Partition failed with error message: Could not unmount disk."

Can anyone help me? It's driving me crazy.

Thanks.