iOS simulator freezes to blank screen

I was having trouble getting the iOS 7.1 simulator to load properly. It would start but then just freeze on a blank screen (this is launched from Appcelerator Titanium but seemed to occur irrespective). Nothing would work – not even the Hardware -> Home button.

After a bit of investigation I found the following message when running ios-sim:

dyld: Library not loaded: 


Turns out I had set a different DYLD_LIBRARY_PATH (to /usr/lib) in my profile (~/.profile) for Python and this was causing this behaviour. A quick way to check is to sudo as another user (e.g. sudo su as root) and run ios-sim and see if you get the same error without your profile loading.