If you are receiving a warning like: “Found conflicts between different versions of the same dependent assembly” when compiling your application, it’s because you are referencing different versions of an assembly in two different project of your solution.
In my case, it was a System.Drawing reference, which was not properly updated when switched to .Net Framework 4.0, and still was pointing to the 2.0 version of the System.Drawing DLL.
Visual Studio won´t tell you which reference is causing the issue (it’s admitted by Microsoft dev. team that they will probably include that feature in the future), so you have to search for it manually. It will tell you anyway in which project the wrong reference is, so you only have to look there.