I have this issue every time I open Xamarin.Studio. The syntax highlighting, autocomplete, and right-click menu does recognize any references or usings in my files.
Exceptions: Current File's Namespace, Compiles fine.
The only thing I can do to get it to go away, is to "reference" Mono.Android - even though it already exists in the references. (I've removed and re-added it).
Any assistance is appreciated. No one else in my office seems to get this issue.