Unexpected windows phone application exit without any exception

I have a windows pone application working quite well except when it comes back from Tombstonning, then quite randomly it silently exits after executing the same command some times.

I have set VS2012 to pause on any first chance exception but nothing happens:

I also have handlers for the following events:

this.application.UnhandledException += this.OnApplicationUnhandledException;
this.application.RootFrame.NavigationFailed += this.OnRootFrameNavigationFailed;
AppDomain.CurrentDomain.UnhandledException += CurrentDomainOnUnhandledException;

None of the handlers gets called :S

The only information I have is the following line on the output which does not mean anything to me. Any help would be really good, thanks.

The program '[1040] TaskHost.exe' has exited with code -2147483645 (0x80000003).

EDIT: Finally I tracked down the problem to the following line:

Contract.Requires<ArgumentNullException>(bitmap != null, "Bitmap cannot be null.");

The application is exiting even when the bitmap variable is not null. Any idea?

Seems that this is a defect on the CodeContracts API.

Calling:

Contract.Requires<ArgumentNullException>(bitmap != null, "Bitmap cannot be null.");

makes the application exit sometimes (event with bitmap not null) with the only information being:

The program '[1040] TaskHost.exe' has exited with code -2147483645 (0x80000003).