I am experiencing a wierd one and haven't been able to find an answer.
I'm using Visual Studio 2015 and C#.
I have 3 solutions. They all include the same common project. In the first 2 projects all is well and happy. In the 3rd the common project loses its reference to System. There have been no changes made to the project.
Does anyone know why this happens, and how I can fix it?
Thanks
Steve