Hi
We have noticed a difference how Nokia Lumia 900 device operates when compared to Windows Phone 7.1 development emulator and real HTC device (HTC Trophy). We are developing Silverlight + XNA application for Windows phone 7.1 (Mango). We have noticed that NavigationService.Navigate produces crashes on Lumia 900 devices that we are not getting on emulator or with HTC devices. Our program uses multiple different xaml -pages and we move between pages using navigationService as follows e.g.

(1)
Code:
 NavigationService.Navigate(new Uri("/Results_Page.xaml", UriKind.Relative));
We cannot use NavigationService.GoBack since application logic is somewhat complex and we might need to jump to different page where we originally came from. Therefore we are making sure that there are no extra backEntries or any other trash that could cause issues when navigating (this seems to be the case on emulator/HTC). Now what happens on Lumia 900 is that navigation works quite nicely in the begging, but when memory loads are getting bigger (this is my assumption only) the above code (1) causes the program to crash. This crash is specific to Lumia 900 device and it does not occur in HTC -device nor in WP7 emulator. Below a partial stacktrace

Code:
JuJu_Race.dll!JuJu_Race.App.RootFrame_NavigationFailed(object sender, System.Windows.Navigation.NavigationFailedEventArgs e) Line 140	C#
 	Microsoft.Phone.dll!System.Windows.Navigation.NavigationService.RaiseNavigationFailed(System.Uri uri, System.Exception exception) + 0x52 bytes	
 	Microsoft.Phone.dll!System.Windows.Navigation.NavigationService.ContentLoader_BeginLoad_Callback(System.IAsyncResult result) + 0x145 bytes	
 	Microsoft.Phone.dll!System.Windows.Navigation.PageResourceContentLoader.BeginLoad_OnUIThread(System.AsyncCallback userCallback, System.Windows.Navigation.PageResourceContentLoader.PageResourceContentLoaderAsyncResult result) + 0x116 bytes	
 	Microsoft.Phone.dll!System.Windows.Navigation.PageResourceContentLoader.BeginLoad.AnonymousMethod__0(object args) + 0x11 bytes	
 	mscorlib.dll!System.Reflection.RuntimeMethodInfo.InternalInvoke(System.Reflection.RuntimeMethodInfo rtmi, object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, object parameters, System.Globalization.CultureInfo culture, bool isBinderDefault, System.Reflection.Assembly caller, bool verifyAccess, ref System.Threading.StackCrawlMark stackMark)	
 	mscorlib.dll!System.Reflection.RuntimeMethodInfo.InternalInvoke(object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, object[] parameters, System.Globalization.CultureInfo culture, ref System.Threading.StackCrawlMark stackMark) + 0x168 bytes	
 	mscorlib.dll!System.Reflection.MethodBase.Invoke(object obj, object[] parameters) + 0xa bytes	
 	mscorlib.dll!System.Delegate.DynamicInvokeOne(object[] args) + 0x98 bytes	
 	mscorlib.dll!System.MulticastDelegate.DynamicInvokeImpl(object[] args) + 0x8 bytes	
 	mscorlib.dll!System.Delegate.DynamicInvoke(object[] args) + 0x2 bytes	
 	System.Windows.dll!System.Windows.Threading.DispatcherOperation.Invoke() + 0xc bytes	
 	System.Windows.dll!System.Windows.Threading.Dispatcher.Dispatch(System.Windows.Threading.DispatcherPriority priority) + 0x83 bytes	
 	System.Windows.dll!System.Windows.Threading.Dispatcher.OnInvoke(object context) + 0x8 bytes	
 	System.Windows.dll!System.Windows.Hosting.CallbackCookie.Invoke(object[] args) + 0x19 bytes	
 	System.Windows.dll!System.Windows.Hosting.DelegateWrapper.InternalInvoke(object[] args) + 0x2 bytes	
 	System.Windows.RuntimeHost.dll!System.Windows.RuntimeHost.ManagedHost.InvokeDelegate(System.IntPtr pHandle, int nParamCount, System.Windows.Hosting.NativeMethods.ScriptParam[] pParams, ref System.Windows.Hosting.NativeMethods.ScriptParam pResult) + 0x5e bytes
Code:
 
Exception	{"The type 'JuJu_Race.Results_Page', specified in the x:Class of '/Results_Page.xaml' could not be found in any loaded assembly."}
System.Exception {System.InvalidOperationException}

AbsolutePath	'((System.Windows.Navigation.NavigationService)(sender))._currentSource.AbsolutePath' threw an exception of type
'System.InvalidOperationException' string {System.InvalidOperationException}
Interesting is that the above call works just nicely at first but after awhile it crashes. This issue is not specific to Results_Page.xaml. Any navigation will cause this (after a certain time). We need some kind of workaround to this. Our application is almost release ready we just need to get this fixed.