Hey guys. As you can see from my username, im freaking stupid. I made the mistake of running a beta as my main os. this is the last time i fiddle around with things im not familiar with. Im done with betas and alphas. with that being said, i need help downgrading my 2011 macbook air to lion. I tried and read everything. Even the thread thats two below me. I booted into recovery and went to disk utility but when i tried to erase my HD it says "error. cannot unmount disk". After seeing that i assumed, maybe i'll just reinstall the OS on top without erasing. When i went to go reinstall the OS, i realized that the reinstallation is for 10.8 and not for 10.7. There isn't a trace of 10.7 anywhere. My online recovery is now for 10.8. I have no idea what to do guys. Please help here. Belittle away, i deserve it for being so stupid. So recap, my online recovery is now 10.8 and i can't unmount my disk to erase. freaking great. I dont have any time machine back ups of 10.7 either. any luck?