Yesterday I was converting an old work-related project to the new csproj structure (using this very helpful tool by Hans van Bakel). Tackling compilation warnings one by one, I was finally left with this one:

Warning AL1073 Referenced assembly 'mscorlib.dll' targets a different processor

Some Googling revealed that this was related to .resx files and x64 platform targeting. Unfortunately, the workarounds offered on Stack Overflow didn't quite work for me. The warning was replaced by two warnings. The original one, plus this: