Reinstall of Lion didn't do anything?

[slapple]

I just tried to reinstall Lion on my MBP. I rebooted the system and held down the Option key to go into Recovery mode. Then I told it to reinstall Lion onto the Macintosh HD drive. So it spent the next 2.5 hours downloading Lion. Then it rebooted and started installing Lion, and that took 30 minutes. Then it rebooted again, and I was shocked to see the lock screen for the old user I had. I logged in, and it was as if nothing happened. All my browser windows were still open along with the other programs I had open before reinstalling. I thought a reinstall was supposed to make a totally clean system. What the heck happened?

 

[B Gallagher]

I just tried to reinstall Lion on my MBP. I rebooted the system and held down the Option key to go into Recovery mode. Then I told it to reinstall Lion onto the Macintosh HD drive. So it spent the next 2.5 hours downloading Lion. Then it rebooted and started installing Lion, and that took 30 minutes. Then it rebooted again, and I was shocked to see the lock screen for the old user I had. I logged in, and it was as if nothing happened. All my browser windows were still open along with the other programs I had open before reinstalling. I thought a reinstall was supposed to make a totally clean system. What the heck happened?

I could be mistaken, but I believe that what Lion does if it is already installed on a drive is somewhat similar to the old Archive & Install option - namely, it will reinstall the entire operating system, but leave your user files intact. That would be why your username, browser settings, etc., wouldn't have changed, as the "reinstall" only applied to Lion, not your user account.

If you want to start fresh with a totally clean system (i.e. a blank hard drive), similar to the old Erase & Install option, when you go into recovery mode, go to Utilities (or something like that, from memory), Disk Utility, then choose your internal hard drive and erase it, choosing to format it as Mac OS Extended (Journaled), which is what it should already be.

Just make sure you have a proper backup (or backups) in place. Once you click erase, it's not impossible to get your data back, but it's pretty damn difficult.