I'm seeing many cases of people with both, Air and Pros, where if they go to reinstall the OS for whatever reason..they are met with an error message and pretty much no way to get pass it. Only thing I've seen Apple suggest is to connect a second Mac to do a recovery, which isn't an option for most owners. This is also happening to people who already updated to 11.0.1 after it came out from the box. What do you think Apple will do for a fix on this issue and what are they doing to help those affected?