So, I have this problem with my MacBook Pro Penryn that makes it freeze every 20 hours or so. (It just starts to lock up at one point during the day.) Reinstalling OS X using clean reinstall didn't help either, so I made an appointment at the Apple Store Genius Bar. The guy there told me that he would reinstall OS X and then he would have to take it to run tests on it to see if it did indeed have that 20 hour problem. I was :| to this (since I have to use this machine daily and it was my only machine, and the guy said that they didn't have any loaners.) But I let the guy reinstall OS X on the machine, and he installed the Desktop version of OS X, which I noticed when my trackpad was being sluggish and that multi-touch support stopped working. (Double finger scroll, etc.) So I went to another Apple Store and hoped for better luck. Guy said the same thing, but had a "new" idea of reinstalling OS X and doing some stuff to it. I said OK, he reinstalled OS X, and turns out that the OS X installer WAS the right one for laptops (not desktops this time.) However, when I went home, System Preferences was messed up, and keychain items stopped working (my login keychain was gone, and trying to do Keychain First Aid resulted in a The application Keychain Agent quit unexpectedly. So now I'm at home reinstalling OS X for what is probably the third time today from my own DVD. Four and a half hours at the Apple Store and about two more hours now (not to mention another hour or two getting all my data restored from my backup) wasted.