I've seen numerous threads on the subject but none of the solutions work for me (clean/rename/delete/recreate/etc). I'm on a Mac running OS X 10.9.1, and Xamarin Studio version 4.2.2 with all the latest updates as of this writing.
Just following the Android "Hello, World" tutorial, where it first introduces the Resource class in the "Creating String Resources" section:
/Library/Frameworks/Mono.framework/External/xbuild/Xamarin/Android/Xamarin.Android.Common.targets: Error: Tool exited with code: 1. Output: obj/Debug/res/layout/main.xml:1: error: Error: No resource found that matches the given name (at 'text' with value '@string/hello'). (Hello_World_Android)
Looking at the Resource.designer.cs file, it has not been regenerated, it still has the default resources in there from the initial project creation.
This is a blocker for me.