loadView, didReceiveMemoryWarning, and an NSLock bug

Question

1. I simulate a memory warning on the simulator.
2. SettingsViewController releases it's view since it is not showing.

3. I display the SettingsViewController view, loadView gets called, and then in viewDidLoad, the program hangs on the following line of code:

   self.unitSwitch.selectedSegmentIndex = 1;

On my terminal, I get this message:

-[NSLock lock]: deadlock (<NSLock: 0x1461f40> '(null)')

Break on _NSLockError() to debug. 

Another interesting thing is this. My app has a TabBarController, and the program will only freeze when switching to the SettingsViewController from 3/4 of the other screens.

What's going on here?