I partitioned my harddrive to put Windows XP on it. Then I decided I didn't want to put Windows XP on it. So I unpartitioned the harddrive using Disk Utility and my Mac shows that the hard drive is not partitioned, however, when I turn on my computer I have to hold down the "Option" button in order for me to choose to boot from the Macintosh HD. If I don't hold down the "Option" button a black screen shows up that says "Please enter a bootable disk" or something of that nature. Was just wondering if there was anyway that I could fix this problem! Thanks for all your help. P.S. The reason I want to fix it is because I plan on putting Windows 7 on my Macbook using VMWare.