I've just finished off an app for the iPhone which, until today, ran fine on the iPhone simulator and actual devices.

I tried changing the xib which is loaded in the applicationDidFinishLaunching method in my application delegate class - all I did was change the string in initWithNibName.

When I launch the app on the simulator, the Default.png image is shown, then the app crashes with an uncaught exception. When running on a device, the Default.png image is shown for about 10 seconds, the UI is never loaded and I get 'GDB: Program received signal: "SIGABRT".' on the Xcode status bar. Debugging shows that applicationDidFinishLaunching is never actually reached before the app crashes.

Setting the starting xib back to the original solves the issue, but now I've made a change and saved it in the Interface Builder and the app shows the same issues as above - I've made no code changes at all.

Is this a memory issue, or a known issue of a common mistake?

NOTE: I've made no code changes whatsoever, and the only changes I've made to the xib are cosmetic, the IBOutlets are all intact.