Namespace conflict name - unit tests using Visual Studio 2010

I am working on a project written in C++ for which i want to add unit tests using Visual Studio 2010.

After i create a test project, add it to the solution and write my unit test, i am getting the following error:

Error   1   error C2365: 'MS' : redefinition; previous definition was 'namespace'

MS is used in an enum in my project.

Is it possible to get rid of this error without changing the original sources? Is there any change that i can do to the test project?