I've tested this with multiple projects and it even happens with the HelloWorld sample. When I open a layout resource file with the layout editor, Xamarin Studio crashes with the following information:
Problem Event Name: APPCRASH
Application Name: XamarinStudio.exe
Application Version: 188.8.131.52
Application Timestamp: 5202caca
Fault Module Name: libglib-2.0-0.dll
Fault Module Version: 184.108.40.206
Fault Module Timestamp: 50b4fecd
Exception Code: 40000015
Exception Offset: 0005e17b
OS Version: 6.1.7601.2.1.0.768.3
Locale ID: 2057
Additional Information 1: 4c60
Additional Information 2: 4c609b9ee6afc206f5625ac60d945848
Additional Information 3: 4485
Additional Information 4: 448588a8947829fb230815c328c1a6d2
I have the latest stable releases of Xamarin Studio (4.0.12) and Xamarin.Android (4.8.1) on Windows 7, I've also tried the latest releases on both the Beta and Alpha channels but the problem still exists. This seems to have started happening from nowhere and I've tried just about everything, including a re-install of both Studio and Xamarin.Android.
The IDE log file also contains this dubious little entry:
ERROR [2013-09-27 15:09:26Z]: Add-in error (MonoDevelop.Xamarin.Ide,4.0.12): Error while getting object for node in path '/MonoDevelop/DesignerSupport/PropertyProviders'.
System.InvalidOperationException: Type 'Xamarin.Ide.Components.ComponentReferencePropertyProvider' not found in add-in 'MonoDevelop.Xamarin.Ide,4.0.12'
at Mono.Addins.RuntimeAddin.GetType(String typeName, Boolean throwIfNotFound)
at Mono.Addins.InstanceExtensionNode.GetInstance(Type expectedType)
at Mono.Addins.ExtensionNode.GetChildObjectsInternal(Type arrayElementType, Boolean reuseCachedInstance)
Any help would be greatly appreciated.