How to eliminate certain annoying message during framework source code debugging.

Question

Dear ladies and sirs.

While debugging the framework source code I always get this annoying message from the studio:

Some bytes have been replaced with the Unicode substitution character while loading file C:\Users\markk\AppData\Local\Temp\SymbolCache\src\source.NET\4\DEVDIV_TFS\Dev10\Releases\RTMRel\ndp\fx\src\Core\Microsoft\Scripting\Compiler\VariableBinder.cs\1305376\VariableBinder.cs with Unicode (UTF-8) encoding. Saving the file will not preserve the original file contents.

As a result, the source code is open in modified mode (with an asterisk in the name). This is hugely annoying.

Does anyone know how to make it go away? I am using VS2010.

Thanks.