Okay guys, I really need some help. I bought a Macbook Pro with Lion installed. I setup Windows with Bootcamp and ran that for a while. Now, I wanted to clean install JUST Macosx for school in two days. I deleted the Bootcamp partition with Disk Utility, like an idiot. I made a Lion Recovery External Drive and I'm trying to just erase the entire hard drive. Whenever I go to do that though, it says "Unable to unmount." I'm really stuck, and I could use some help. All I want to do is delete everything off this hard drive and start again. Please help, anyone. And thank you so much!