This is my first time posting. I've never really had a problem with my MacBook air until the other day. I have the late 2010 edition. I was having trouble starting up after sleep. So I checked the system pref and made sure the installed hard drive was selected. But it still had trouble booting up. So I ran the first aid disk repair using the disk utility and no problem was detected. But it still had trouble starting up. I was able to backup my hd the other day so I wanted to Install the os x using the memory stick. But it would not detect the factory flash drive. It says the hd is not mounted. How do I mount the hard drive? So I can finish the install of Mac os x. Any help would be great.