The line of code that causes it any place referencing type `System.Collections.Generic.Dictionary` whether as a variable type, or in a Using Declaration.

This Using declaration worked fine and made my classes less disgusting than having to write `System.Collections.Generic.Dictionary<string, object>` in 100 places in my class. Taking the Using declarations out does not solve my problem, it just moves it to the places where the dictionary type is used in my method parameters.

Full error text:

```
CS0433  The type 'Dictionary<TKey, TValue>' exists in both
'System.Collections, Version=4.0.10.0, Culture=neutral,
  PublicKeyToken=b03f5f7f11d50a3a' 
 and 
'mscorlib, Version=4.0.0.0, Culture=neutral, 
 PublicKeyToken=b77a5c561934e089'   ProjectName.DNX 

```

This error occurs in ASP.NET 5 MVC 6 template based projects using DNX 1.0.0-beta7, having some Model and Controller classes that reference generic collection types. The project.json is set thus:

```
  "frameworks": {
    "dnx451": { }
  }

```

The sample problem occurs if you just have it say:

```
  "frameworks": {
    "dotnet": { }
  }

```

* The line of code that causes it is a Using declaration, a type alias of sorts, that worked fine until I try to convert a beta6 project to beta7.
* Conversion proceeds until I try to add these using JsonDictionary aliases, then compilation breaks.

I have searched this error code and it has a long and Inglorious history in ASP.NET. 

What causes this problem? And how can I fix it, since I can't remove mscorlib from my project, nor can I remove System.Collections?